To ask for help packing / dressing?

[Almost2026]

We have a trip to London coming up. We are staying one night, doing the crystal maze experience on day 1, theatre that evening and probably shopping the next day.
I’m trying to pack really light so we don’t have to leave luggage anywhere and can carry a backpack.
Im size 18 bottom / 16/14 top - what would you wear? Especially for Crystal Maze and theatre to avoid taking too many outfits / shoes!

I'd wear trainers with something comfortable that you can move around in; the Crystal Maze thing might be quite physical?

Plus sitting in a theatre seat for two or three hours is a lot more pleasant in comfortable clothing - you can always bring a clean tshirt or similar for the next day