What to do for stepdaughters birthday? (UK)

Okay, so my stepdaughter is turning 11 next month, and we’re struggling to think of things to do with her on her birthday. I’m expecting my first bio child next month too, so I want to take it easy just in case of early labour.

Any ideas on what to do that will be manageable while heavily pregnant, yet still enjoyable for my stepdaughter’s birthday? My partner is thinking of a birthday party, but I’m not too keen as it’ll be a hell of a job to clean up afterwards.