My daughter was 22 months when my twins were born, so similar age gap. It is totally doable (we survived! Although the twins are still only 3, so some days still feel like the eye of the storm
).
I think I’d be asking for paternity to start when you’re home, too - realistically you’ll need him a lot less in hospital. Is there any other help you can call in? Beg each and every favour you can, especially anyone who’s happy to do things with your daughter while you look after the baby. Bear in mind there’s a high chance of a C section and if that happens you won’t be able to lift your DD (I found that really hard because she was still in a cot... yours is a bit older so if she’s not already it might be worth thinking about getting her into a toddler bed). We also had quite a few different members of family come and stay at various times while I was recovering, just to help with lifting, entertaining DD while I was establishing feeding etc.
I breastfed mine til they were 10 months, so it can definitely be done, but I would recommend combination feeding if you’re happy to - we always gave the twins a bottle at bed time & here and there through the day. Plus it makes it easier for you to leave the house by yourself if you ever need to!
For naps when they were tiny I used to put them in the double pram in the lounge while I’d play with DD in another room. As soon as they could I put them upstairs to sleep tho - I got them quite ‘routiney’ quite early for sheer survival!
Child proof the shit out of the house (locks on any room you want to keep them out of altogether, all cupboards locked, anything breakable out of reach) so that you don’t feel you have to watch DD constantly. We were lucky enough to have a separate dining room which we changed into a play room and put baby gates on, so there was one space I could leave DD while I was putting the twins down for a nap or whatever, and know she was safe. But honestly if we hadn’t had a dining room, I think I would have sacrificed the lounge - the play room was a lifesaver!
As soon as you’re physically recovered from the birth get out every day if you possibly can, and scout out all the parks and other outings in walking distance - getting in and out of cars with three kids is a massive faff. Also work out which places you can fit a double buggy into!
Never beat yourself up about using CBeebies as a babysitter if you need to.
And if you can possibly afford to, get a cleaner! 