I had 2 under 2. They're now 1 and 3. Absolute sweethearts and the oldest dotes on the youngest.
It was complicated because DS had a speech delay and he was barely talking (when DD was born, DS had about 10 words at this point, and five of them were types of vehicle, the rest were snack names) or understanding us. Before I was ready to give birth I bought my oldest (DS) a Baby Annabel doll, a bottle and dodie and hid it away. When I came back from the hospital with DD, I gave DS the doll etc, and he was really excited that he got to have a new baby and mummy got one too (what are the odds, eh?) so I put him in a role where he wasn't in competition with his sister, but was a caregiver (with zero actual responsibility ofc) so he saw his sister as someone to help rather than someone taking his mummy away.
Due to COVID I gave birth alone and was alone in hospital with DD for 3 days (lockdown ward, IDK if you had them in England), I'd never been away from DS before then. DS had conjunctivitis when DD was born, and a horrendous chest infection that turned out to be whooping cough, and DS and DH ended up sleeping in our room while me and DD were in DS's room sharing the single bed for two weeks until DS was better and not contagious, so apart from 2 hours when DD and I returned from hospital in a taxi, none of us saw each other for the first 17 days. I think making sure DS didn't feel like his sister had taken his mummy away was the reason that everything was fine after that initial period.
As soon as DD was 4 weeks old, DH had to go away to England for work, leaving me alone with the babies in Ireland. I took the PHN's (HV's) advice and got out every day, even just walking around the estate with the double buggy. DD was a delightful sleeper during the day (not so much at night), so I used to park her in her buggy and focus on DS while we played together.
The best piece of advice I got when I was pregnant was whenever there's a conflict between DC1 and 2 both needing you at the same time, prioritise DC1 where possible for the first couple of months, as the oldest child is used to having you on tap and it stops resentment building while they transition to sharing you. The other thing I'd suggest is if your DH won't be on hand much, avoid a CS at all costs so you can still lift your toddler in and out of car seat/pushchair.
Also, get a double buggy. We had the cheapest - the Joie Aire. Phenomenal, light enough, easy to push one-handed, and fitted in the boot of our hatchback. Buggy boards and baby wraps are all well and good but some days you will just need to pop them both in the pushchair to get somewhere and get something done.