razal

Good luck in finding a position, it aint gonna be easy though , your mate sounds like he,s protecting his ass a bit to me ?
You are going to college because you know little about plumbing , you dont ever need to apologise for that. Do the course and hassle for a job, most of the bigger companies will want a minimum of C,s in gcse,s, if you aint got that think also of getting better results through evening classes perhaps.
You may find once you learn some plumbing and have a bit of hands on experience that it aint for you or you may really like it, in either case I say best of luck to you.