Parents in law on holiday

It's the type of ILs that is the problem. (And the DH but that's a separate issue.)
Yes, it's very rude to invite yourself along to other people's holiday but some ILs such as the OP's seem to think it's fine. Needs to be addressed, sadly.
It's also how the actual holiday is envisaged. Whenever we have gone away with other people, (not ILS but other family or friends, usually to a large villa) it has always been very clear from the start that we are not all joined at the hip.
It's perfectly fine to do your own thing. Lounge at the pool or go to the beach, or shopping, or do cultural things. By yourself, with your OH, or anyone else in the group but just recognising people want to do different things.
So it's all agreed at the outset and no-one can get snippy about it.
We may meet up for some or even most evening meals but it's not compulsory .
The thought of going about mob-handed all the time, traipsing en masse round a church or market or water-park is ghastly. Even if it's just six of you, it's too many.
You need to have that awkward conversation, I'm afraid. Better the two of you do it rather than him alone and have him pin it all on you. 'Well, Siobhan says xxx and you know how she is...'

They'll be dead one day

Sorry but I never understand this point- we will ALL be dead one day. One day OP or her partner will die so by that rationale they are not being unreasonable to want some holidays alone together to make their own personal memories before they die too.

The dead one day thing always sounds like blatant emotional manipulation to me, never coming from a place of genuine compassion but as a weapon to get what you want and ride roughshod over other people's wishes.

Both my parents are dead. I saw them lots, we loved each other but we never went on holiday with them and I have not one single regret about that. I did plenty for my parents so have zero need to feel any kind of weird guilt. Neither did they pressure me to take them on holiday because they recognised it was important for me to spend time with my own immediate family too. They were very respectful and caring in that regard and I loved them for it.

I know it’s very Mumsnet to hate spending your leisure time with in-laws.

Yes. There’s a reason for that. If the in-laws were perfect holiday companions, people wouldn’t post about the threat.

@DecafDodger I assume grandparents are will probably find a hotel or similar rather than camping

We went on holiday with the ILs years ago. Shared accommodation.

We'd been living apart a lot as DH had a new job and I hadn't moved across due to new born and a child settled in nursery.

So off we went. Didn't get a moment apart, so after a few days when I was really struggling we told them we'd do our own the the next day but could meet them at x later if they wanted.

They followed us. Actually followed us. I pulled over to have a meander around a marina and they parked and waited for us to finish. I kept meandering and meandering waiting for them to go, so they sent BiL to ask how long we'd be.

Honestly it just doesn't work with some people.

People who are not even agile enough to the beach are going camping? I would expect that what they are actually able to do would be quite limited, so can't you and kids do their own thing and meet up for dinner?

Just tell them the wrong dates 😆

Lie about the dates.

@ArthurChristmas22 - you find some of these responses heartbreaking??? Really??? Not everyone gets along like a house on fire with their in-laws. Most have a polite relationship as it is the son/daughter - husband/wife that we have the primary relationship with and not the MiL/FiL relationship.
I like my in-laws but I'm quite happy that even when they were fully able, we were never expected to accompany them on their holiday and vice versa.

Amen!

Absolutely.
I don't invite myself on my son's holidays. I can't imagine starting to do that if/when he has kids.
Before MN I had no idea that people invited themselves on their adult children's holidays, and even less idea that some people think that's ok.
Do people really believe that if a couple has arranged a holiday for themselves and their children, it's perfectly normal for one of the couple's parents to gatecrash?

My in-laws are decent people, but dear god, a joint holiday would have been a nightmare. Their endless quirks, habits, rigid routines and disapproving of things would have been unbearable.

And please stop with the "one day they'll be gone" guilt tripping. You won't be wailing at their graves wishing you'd let them come on your holiday.

The first issue is that your DH will probably not see anything wrong with having his parents on holiday with you as, they are after all his parents and he's probably been on plenty of holidays with them before. So, you need to dissuade your DH of the idea that this is a good idea. You won't want them for babysitting duties and even if they made the suggestion that they would do that, by the time they get there, they are likely to change their minds, be too tired and you'll still not get a break.

I would make it very very clear that if they come on this holiday, you will expect a separate holiday of equal duration where they are not invited so you can relax on that holiday. It's not a holiday when you can't relax.

Then I would plan a visit to the in-laws with DH so that he can tell them that while it might be a lovely idea, unfortunately it's not going to be possible for them to join you on this holiday. Perhaps if they give you some dates that they are available to travel on, you can research some family friendly locations for a weekend or midweek break away while the kids are not in school. Then do a bit of research and present them with say 3 options at different prices and make it clear that they would be expected to contribute to the costs of whichever holiday/break they decide on.

That's how I'd deal with it.

When DS was little we had holidays a bit like this (and we were possibly the ones inviting ourselves!). GPs lived miles away, so didn't see them much. We tagged along on a few holidays, but usually only for a week out of a 2 week holiday. We would book somewhere nearby (did Scilly Isles once and we stayed on different islands). So would meet up a couple of days, so GPs could have fun on the beach etc with DS, but rest of holidays was our time and their time. Obviously, all done with agreement with adults. My proviso used to be though that we would have one holiday with GPs and one without, so could be a weekend break for us or weekend with GPs at somewhere like Center Parcs.

So would it be an option there is only a couple of days overlap, and you just have a few hours with them, or maybe try and arrange a weekend with them another time.

But this should be your holiday first and foremost

Bit rude of them not to at least ask, don't you think?

I think you can do this kindly. Say "that sounds great, we'll be doing beach things with the children during the day but can all meet up in the evening if you are not doing anything else". That way you are setting the ground rules very openly, but keeping options open.

Say no, but maybe offer a weekend away together another time?

You need to have that chat however uncomfortable it is or you won't have a holiday.

We've been quite lucky when we've been away with FiL & youngest BiL. We've shared accommodation and taken separate cars so we've met up for evening meals to catch up and we have shared some costs but we've had mainly separate holidays other than a couple of agreed days out and last day breakfasts etc. Forced time together would not improve matters.

I used to wait for DH to say no, he was never able to do it effectively, either putting it off until the last minute or not explaining properly.

I think you have to nip in the bud yourself right now. You are a couple and asking one half to come on holiday isn't on. its also inviting themselves behind your back which is a bloody cheek and there's a reason why they asked DH and not you, because they knew he'd find it harder to say no.

I think you have to be the Bad Guy, take the hit and make sure you ring fence your holidays for yourself. Otherwise they will think its OK to keep asking your DH and jumping in on your plans.
Take courage in both hands and email them directly yourself. Say everything you said in your post. Writing is better so they have time to read and digest. And then prepare DH to have the talk when they've read it. It's perfectly reasonable and if they take offence its on them.

"Hi Inlaws. I hear you've told DH that you want to stay nearby when we are on holiday. I'm so sorry but we planned a quiet relaxing getaway from it all with just the DC and us on our own and we want to stick to that plan.
It's our only week's holiday this year and we've been looking forward to this so much and we don't want to suddenly change or expand our plans now. We've already spent ages talking about exactly how we want to spend this break and don't think you would find the days out and activities we have planned for ourselves suitable for you.
Maybe later in the year, a weekend away planned by all of us together, would be more suitable for everyone instead. "

Weeks away with the DC just on our own were brilliant to have the time and space to really play with them. When they were small their speech really developed during that time. It was also a time when I had DH to myself and we were really able to relax. When we did go away with others it turned into a marathon of cooking, entertaining and endless chatter, which was exhausting.

Stand firm OP and happy holidays!

Sums up my thoughts exactly!

Depends on in-laws. Some are lovely; mine were a nightmare. One holiday with them and I was shaking with rage. They thought the trip was an all-inclusive (courtesy of us) and full housekeeping and cooking (courtesy of yours truly).

Another rage-filled trip was when I was going away for a week as an adult with my parents. Dsis invited her dd along - by herself. Dm was too weak to say no, so we had a very difficult 4-year-old dictating the whole itinerary (whilst dsis and bil had a child-free week).

One of my regrets in life is having spent so many holidays with family when we never had a great time with them. If I had my time over, I would change this and significantly reduce the amount of family holidays. OP, I would nip this in the bud sooner rather than later. I think it's perfectly reasonable not to have to share your holiday.

It is rude to invite yourself on someone's holiday. It isn't unkind to say no.

This. I really hope he feels able to nip this in the bud, your family holiday deserves to be protected. X

Christ maybe they just want to amble around St Austell

No-one wants to amble around St Austell 😂

Difficult one. We took MIL & FIL on holiday to villa in Spain they kicked up a fuss because we had been with my parents a nd wanted the same. However we ended up paying for everything I did object to paying for their flights and they weren't happy about that. My parents went half on everything even the hire car. They complained about the heat. Our 5 year old watching cartoons. Price of bread. Any where we suggested to go they pulled faces. In the end I would just say where we going if they wanted to come if not they could stay put. It was a nightmare. FIL when we went out for a meal complained about everything. Wanted menu in English which not all restaurants had. Then the food wasn t good enough. If I was you, lI would just say not this time we'll arrange something later in the year and go to centre parks or similar. Good luck.