AIBU to not go to the team day?

I think YABU mainly because you’re not claiming the time back. This is what you are resenting (or appear to be). Put your boundaries in place, attend especially if it is one of the two occasions this month and ask to take the time off this week. Simple.

the work will have to wait (easier said than done I know but the company in your words are treating you badly, don’t be a martyr to them and start looking for alternative employment)

In your shoes I’d find out exactly what’s involved before I make a decision. If it’s just a send off then I think it’s fine not to bother but if it’s more than that (team building exercises, meetings etc) I don’t think it’s wise not to go just because of the early start. I don’t know about your company but we are all under a bit more pressure to attend the office, it might be a good chance to get the inside line on the merger and you don’t want to get labelled someone who won’t travel. Plus you’re not being asked to do it frequently. I’d do half the journey on Sunday and then get back late on Monday night.

I wouldn't let the "showing yourself to be a team player because of forthcoming redundancies " factor into your decision.
You're just a number to your company and any redundancies are likely to be made based on factors outside your control.

Drive down on the Monday, stay overnight and travel back on the Tuesday?

Spending 7-8 hours of your own time per month travelling isn’t long, we used to call this commuting before remote working became a thing. I work remotely but still have to travel occasionally, on my own time, but with expenses paid.

I would say your car is off the road and as there are rail strikes you won’t be able to travel down south for the day. Say you can join them in an online teams meeting

Last month I spent around 7-8 hours of my own time just travelling
I think with remote working, some young people have not taken on board that it used to be completely normal to travel to work. If you weren't working remotely, and were "down south", it would be very common to spend 2 hours every day for the two 1 hour journeys to and from work. So in a normal week, you would have more "unpaid" travel time than you are currently being asked to do in a month. And complaining about.

I think it is ok to occasionally miss a session if you have personal issues caused by the travel time, but not just because you prefer a lie-in. If you are even offered time in lieu then take it, so you extend the next weekend, that is a great perk rather than something to moan about. It's also ok to ask for future sessions to be held mid-week if that is easier for you.

Surely if it's a large company they'll pay your travel time (or time off in lieu) and overnight accommodation on the Sunday for a 9am start 5 hours away from your normal location? If not then you're being perfectly reasonable to decline.

Every time this type of question is asked on here I think it is relevant to ask why you are working for a company that is so many hours travel away, when it clearly isn't a fully remote role.

If you either a) applied for a job where there were meetings once or twice a month at sites / offices that are 5 hours away or b) had the job and then moved 5 hours away, then I'd say that really is a choice you made, and if the expectation is that everyone is at these meetings once or twice a month, it isn't the employer's problem that you chose to live so far from your work.

OTOH, if you were working happily in a local job and your branch closed, then it is clearly a much bigger ask, and that is a lot of flexibility they are asking for, from someone in a relatively junior role.

Well you're an adult with a job so you should be able to work it out. However hee's my take: it's a one-off, you might be seeing some of them IRL for the last time, and who knows who is looking at this and thinking "hmm, not a team player, lives too far away and thinks attending some events is a pain" and planning a redundancy accordingly.

Sometimes you suck up the sacrifice of a half a day of your weekend because the event, the networking, the people, the effort etc are worth it. Sometimes you don't. So make the choice. (I would go in your shoes)

It's up to you obviously but it does make me wonder why you chose to work when the majority of the sites and events are 5 hours away anyway.

Can’t you travel back during working hours on the Tuesday? And / or negotiate a later start to the team thing on the Monday - maybe a team lunch? You’re travelling for work, after all.

What does your contract say? Are you based in a particular office and have to attend elsewhere ? Then they need to pay you travel time and costs.

I think given the day and distance they should pay the travel time on Sunday, overnight time and also the accommodation. Especially as your wage isn't high.

When we have this kind of event, we Teams the people in who can't reasonably travel. Would that be an option?

I don't think it's unreasonable for your employer to organise the team day as long as they give you time in lieu to cover the travel time. The workload etc isn't your problem, the day was organised by your manager, so you should always take it.

That said, if you don't want to go then now is the time to remember that very important dentist appointment or family commitment you cannot miss on Monday 5pm.

You said your employer gives you time back for travel, so I don't see what difference it would make to travel down on the Sunday and get the time back, or travel on the Monday afternoon (if the event was on Tuesday). Either way, you'll have 5ish hours taken from your working week in which you will be paid, but will be travelling rather than working. You said your work piles up if you take time back, but it would do the same if you travelled during work time surely? Also I'm sure if the company gave everyone a free day of annual leave you wouldn't decline to take it based on workload. It sounds annoying but unless you had a reason such as disability, health, lack of childcare, caring responsibilities it would likely be frowned upon not to go. It sounds like it's just not something that interests you. (Maybe that's acceptable in your workplace, or maybe it doesn't matter anyway if your employment will end soon).

Why would I apologise?

You did a lot of unpaid work so everyone should? No thanks, although I accept your apology.

I dont see see her childcare or her pregnancy being anyone else's problem. It needs to be fair on everyone. Also can't believe you aren't paid for certain parts.

Yeah I wouldn't do that for a job worth 26k.

What are your company policies about driving hrs as I would not want to drive for c10hrs in one day and I wouldn't spend my Sunday driving for work either so would be there for a few hours in the afternoon and then expect company paid for dinner and hotel followed by travel back within work time

Feigning that I would book a days AL to just moot the whole scenario

Yanbu, I’ve turned down events like that for similar reasons.

Completely reasonable, especially at such short notice.

Take the Friday before off as sick with D&V.
Then no one will question you when you say that on Monday that you cant come as you dont want to pass it on.

Your salary doesn't warrant the travel cost or time, send your apologies and contribute to the leaving gift and you're good.

If work really want you to attend they can pay for your travel, hotel and extra hours on the road.

Yanbu, along with the other 1-2 x a month travels that's a ridiculous amount of travel on your own time to be expecting for a 26k job and I wouldn't be feeling particularly accommodating in the circumstances you have described