I think riding schools are over reated lol I Started going to a riding school at the age of 5, Admitedly I learnt alot but then you hit a brick wall, everyone does. You get to a point where you have learnt enough and you cannot pregress on, just have to carry on doing the same old things!
I quit when I was 12/13 for 3 years, then came back to it by starting working at a livery yard and buying a horse. This helped with my confidence on the ground aswel as being able to ride every now and again, then I stopped that and sold my horse to go to college then to start work full time and decided last year to go back to it as I was getting to an age where if I wanted to compete properly I would have to do it now or never!
I had a few lessons but really didnt learn anything! So I decided to go back to horse ownership. In Feb this year I bought Star, 16.3hh tb Mare and I learn so much more from owning her than any riding school would ever be able to teach me! I still have occasional lessons on Star just so that I know we are both working properly and getting the most out of eachother but that is it.

I agree that loaning would be a terrible idea for now or owning as you need some experience as it isnt just the riding when it comes to looking after a horse 24 hours a day! Very stressful with your first for example if they cut themselves, knowing what to do without panicking and thinking they are gonna die from a scratch! lol (I done this hehe) And knowing what to feed them and in what amounts and how to muck out and all things that are involved in it.

Have a few lessons and see how you feel! You will either love it or hate it!
Good luck