You'll do great, my friend!!
I made the silly mistake of choosing the BTEC option after getting similar GCSEs to yourself, because I had little motivation to do work in Year 12. That's bitten me in the back now, in Year 13, because I really want to do well but my Year 12 grades are going to hinder me. I'm so glad to hear that, despite what others say, you've done well in your AS Levels and, honestly, A2 is not a huge step up from AS. Keep putting in the effort, revise revise revise, and you'll succeed!!
Also, a quick word to the wise. Studying in the UK is a wonderful idea, but just because the university says you need (For example) AAA to get in, you can probably get in with AAB or even ABB, just so long as you prove how motivated your are in the subject you want to take. What do you want to take, anyway?