Out of curiosity, if i were to do BTEC perfomance at A-level, where could it lead me? In fact, what can you do with even a standard A-level in music other than busk and be in small-time bands.

Oh...wait, i need no qualifications for either of those...
Get a job in the technical music side of the trade.
Im planning to take music tech so i can become a sound engineer and eventually work up to a music producer.

My friend was looking into becoming a session drummer, very hard to get into because its so popular but a music A level would help.
I know some people who do the performance course, and it's fairly useless. All you do is play covers all day. If you want a course that will get you somewhere, try the BTEC Music Tech course.
Fucking nowhere.
The will to neither strive nor cry,
The power to feel with others give.
Calm, calm me more; nor let me die
Before I have begun to live.

-Matthew Arnold

Arguments are to be avoided; they are always vulgar and often convincing.