Studying Abroad (From US to UK)

I'm currently a junior in high school, and I've recently started looking into colleges out of the US and there's a few that look amazing. I just want to know other peoples' opinions and experience, whether it's a good idea, how hard it is, what I should do in preparation, basic information about the UK education system, scholarships/finances, and really just anything you think is important.

I really want to study animal behaviour/ethology and horse training. There are a few colleges in the US (Findlay, Centenary, Lake Erie, Emory & Henry, MSU, ...) but not only are they much more expensive, they also only have equine degrees. I've only recently thought about animal behaviour/ethology, so I haven't been looking into colleges for that in the US. But, in the UK, the first college I looked at (Hartpury) has so many majors that I would love to take (Animal Behaviour and Welfare, Equine Science, Equestrian Sports Coaching, Equine Behaviour and Welfare, ...). It also seems so much cheaper, and I'm kind of interested in living out of the US.