To be a bit horrified by DHs suggestion that he works from home FT?

Exactly this. Your home is your home. It’s not a workplace.

I think as it's really affecting you on a day to day basis what you should do is put down some rules.
He has to work in a space where you can't hear him,
he has to have noise cancelling earphones and
he can't have his calls on loudspeaker.
He also cannot keep popping in and out to you and the kids except at lunchtime ( which you will not be expected to prepare unless you want to)
You will not be expected to change your daily activities with the children
You will not be expected to remain quiet and keep the kids quiet because it disturbs daddy
You will spend the day as you wish,in or out of the house, you'll not be made to feel a nuisance in your own home.
Put these conditions to him and trial a week. Make sure he knows you're not agreeing to anything yet. Stick to the rules strictly.
At the end of the week/ trial period he'll probably decide for himself that he can't do it in a way that won't mean you have to change your day.
Have a rule, maybe 3/5 strikes and it's off.

I get it OP. I work full-time over 4 days and previously had lived alone for several years. My partner moved in about 18 months ago and works from home and I can’t tell you how much it gets to me and I had no idea I would feel like this.

As he is on his own all day he doesn’t feel like he needs his own space, I on the other hand, crave it. Even on the odd occasion he goes into the office he is home by 12pm and he’s very loud on his phone calls even though he’s in his own room. If I want a day off or week off, I’m still never on my own.

I know I’m probably unreasonable in feeling like I do but I think it’s because I’ve lived alone for so long. I need more alone time and some silence!

I could work from home as we work together in business and have the room, but I don't- I have a desk in town and he works from home and has separate garage conversion.

Like others have said if I'm at home he's in and out relaying every chat/email etc and it gets tedious and to be honest I think you can see too much of someone and then gave little to talk about .

I totally get that feeling OP about not being able to relax -

My Dh is self employed, has always worked at home, in various offices, in cafes, libraries etc. Works odd hours. During lockdown he was always at home as vulnerable. Now he's going back to offices and it's great because when he comes home he's been out and seen different people, different things, been on public transport, bought coffee out or whatever little thing so it's more fun to catch up after. When he's on the phone or zoom at he's incredibly loud 😣I have to shut 2 doors! 😀I think I'm much quieter.

Now ds largely wfh but doesn't disturb anyone and largely different hours.

Some people are more of a "presence" than others.

Oh good God no. And especially not with young children. It’s bad enough having men lolling around the house when they are not working and could potentially be pressed into some kind of use.
I know some couples both wfh and seem to like it but I always think it must be so boring and a passion killer too.
Say no! It’s your home not an office.

How did you cope during lockdown?

It only works when you have dedicated office/workspace sensibly located in your home. Eg a room at the side/upstairs, not somewhere people are expecting to barge through constantly, or a garden office

Thankfully, DH hated WFH and managed to wangle a way back to the office very early on in lockdown and has continued ever since. Adult DS, however, has gone from a customer facing office job to a WFH office job. Even though he stays at his desk in his room, except when he comes out at lunchtime, it drives me mad - and I haven't got any small children to keep quiet. I find myself not hoovering or cleaning his end of the house for fear of making a noise. And don't get me started on the mess he makes in my kitchen at lunchtime but only has time to partially clean up!
I feel your pain OP.

Just be blunt with dh not to judge and then brazen it out. You do get used to it. My mum is always doing stuff - cleaning, cooking, writing lists etc so doing nothing feels naughty. Dh quite enjoys doing nothing occasionally so he’s thankfully onboard.

I understand. Dh wfh 5 days a week and I do 2. I rarely get any time in the house alone. I’m actually used to it now. We did have a conversation that if I had a day off and stayed in my pjs until lunch or watched crap TV etc he wants to judge me. Work is very busy - NHS - and I’m studying a post grad course plus 3dc. I’m not lazy but initially felt guilty. He also shuts himself away in the study so that helps. I quite like my own company but that doesn’t really happen at the moment.

The weekend is literally "a couple of days" where you get to enjoy your home as a home, free of work. You claiming you don't get that.

And it's rich to call me provocative when you're talking about breaking up your children's family because their father works from home. Good luck explaining that one to them when they're older.

I WFH every day and DH 2 or 3 times a week. Kids at school then wrap around afterwards so they're never around. I'm struggling to understand all the challenges a bit but then we both just work in our designated spaces in the house and don't really engage much during the day. DH will make lunch and we might have a chat about who is picking up the kids but that's it.

These bastards and their gainful employment.

@Thecatisannoying I work part time (not from home) and my DH works almost full time (again, not from home he's a builder) but you can bet your life that if he takes a day off, it's when I'm on a day off and just want to be at home myself to do stuff without him constantly being "there"
In fact I find it hard to get motivated to spring clean for example if he's just sitting around playing on his phone.
I don't know how people cope with a WFH partner. I know it's his home, too but still..

I have 2 days at home a week where I do all my lesson planning and marking and some cleaning.

DH works from home 2 days but NEVER on my days off.

He did it once and I drove him crazy with my noise! When I clean I put headphones in and sing loudly and dance (otherwise it's soooo boring!!) and he was so grumpy 😂

"A couple of days enjoying a home as a home is reasonable" Doesn't he get weekends? Or off-days if it's a different rota?

DH and I have both wfh for over 15 years now. Life just happens. We set up our house in a way to make it possible. It’s only the very rare, extremely important meeting that other household members are expected to alter behavior.

i did in DD’s very early years have to stay in my office once I went in there. I packed food and drinks for the day and we made sure I worked somewhere I could get to a bathroom without her seeing me.