Anyone from England help?

I want to take my 2 year old daughter to England with my partner for maybe 3 or 4 days around September/October time. We live in Northern Ireland so I'm not sure where would be best for a little one to get some enjoyment out of it? I've been to Liverpool and Manchester a number of times and I loved it but I've not visited anywhere else! Is there much to do for a toddler there?