Hi Waterlily, we were there in October and had a great time. My top tip is that if you know what to expect you will be fine. Even off peak it will be BUSY, and if you want good seats etc you will need to queue early etc and be prepared for the crowds.
I would suggest you plan what you want to do in advance (I.e. When you arrive and get your 'what's on' guide) and book it early if required.
One night we had dinner at Ludo's Italian and it was great for our 6 and 2.5 year old. Book this is advance too and ask for a tv booth, then the kids can watch a film during dinner to help keep them entertained.