@tony coleman - Forgot to mention. To get in at any Disney Park, you have to reserve your slot in advance.
Technically this means that if you don't, you
will be refused entry into a park even if you have a valid ticket.
You could turn up at the park on the day and book there and then, and in all probability outside the busy summer season, you'd probably be OK.
When we were there in June, we were able to swap a few of our booked days within 24 hours of going. But getting your tickets early and booking what park you need to go to on what day is something to think about.