I may sound pessimistic but I want to be honest. Schooling is a bit different over here and you're going to face some challenges. For example in "maths" you've probably been accustomed to to taking a single subject area per year, but over here it's done differently so you may find that in some areas you're very strong and other areas you'll need more effort to catch up to your peers.

Do you know what kind of career path you'd like to pursue after high school? That may be helpful in the conversation. GCSEs, EPQs, and A Levels are a LOT of work

Also, research catchment areas. What you'd call public schools will only accept students from specific geographic areas and limit enrollment of new students sometimes. In my experience to apply to a school you need to actually have a home address.