Wow, there's a lot to cover from this post!!
Ok, firstly you are not a failure, you received B's in your AS levels, a lot of people would be very, very happy at this!!
If you don't want to go on your second choice course, don't! There is always the option of taking a gap year and reapplying for Uni the next year, doing resits if you don't get your grades, or simply travelling for a bit. I left school far too many years ago with three Bs and a C at Alevel, and had no Uni offers. I went through Clearing and found an excellent course, it is totlly doable, do not panic!!! Grades are not as important in the long run as you'd think!
As for work, I remember awful part time student work, and the best advice I can give you is to keep looking for something new, don't worry about not getting jobs, it happens, eventually you'll be find something better If it seems like you're being bullied at work, talk to someone above your manager!
Thirdly Driving tests, this is not a big deal, it took four attempts for me to pass, and while its expensive to do, remember its quite stressful, and lots of people fail a few times, especially if its late in the month when you take the test!!!
Maybe you should talk to someone, a friend or relative, who won't brush it away, tell them you're upset and want to talk things through, believe me, once someone realises you're upset they'll start to listen more!!
I hope I could be of some help, sorry this is a long reply!!!