I think my favourite place in Norwich has to be the Norwich Theatre Royal https://norwichtheatre.org/whats-on/
They put on truly incredible 🎭 performances there, the shows are amazing!!!
I have seen so many wonderful shows there, some locally produced and some London shows too. Loved watching Evita, Chitty Chitty Bang Bang, pantomimes, and many other wonderfully played events.
The theatre does it’s best to be as accessible as possible for all, and provides a good amount of wheelchair places where you can sit with friends/family and enjoy it all together.
There’s a bar area, and you can eat at the theatre too, or at the Assembly House https://www.assemblyhousenorwich.co.uk next-door.
The theatre have disabled loos, but not a changing places one, however, there are changing places loos nearby which you could use before or after the show I believe.
Norwich has two shopping centres (malls) in the city centre, both near the theatre, and as far as I’m aware both have a changing places loo. I know that Chantry Place does, and I’m 99% sure that Castle Quarter does as well. Castle Quarter’s is more likely to be open layer, as that shopping centre has a cinema which will be used up till late at night.