It really depends, I have taken that train with a buggy and tucked myself in a little alcove it. It was probably for luggage space really but luckily the train was quiet and everyone was using the rack opposite. that was just chance I think though that that space was available in the carriage we happened to get on. I did not get asked to fold because it wasn’t in anyone’s way, but I did have an uncomfortable couple of hours sort of perched next to him on my backpack 🤣
Another time I have gone by the doors, but I knew the train wouldn’t need to open on that side again until we got to KC so it didn’t really matter. Although I was prepared to switch sides depending on if we pulled in on that side at the stations we called at en route.
I get so many trains I have my favourites for ease of travelling with a buggy, LNR and GWR are my least favourites. And yes the steps up are very steep, you really have to boot it up.
Ive got a bugaboo bee, for reference.
Seat sleeping isn’t so bad, I bring him a pillow and a blanket and he stretches his legs over my lap. one time I managed to angle it so my suitcase was level with his seat under the table and he stretched out that way.
I would say just go for it, I’ve never not been able to figure something out. Sometimes we’re in the accessible carriage or where the bikes are supposed to go (annoying there’s always bike space but not dedicated buggy space) obviously have to be fully prepared to move if that space is needed. I usually inform the train guard that I am aware of that regulation and often they tell me of and when a wheelchair user has booked the space.