I'm 18 now and at Uni. I worked in a local shop from the age of 14 right up to 18 when i moved away. I did about 10-20 hours a week, this was also in full time education. It wasn't too bad when i was at school, as i just used to do 2 hours everyday right after school, and the odd bit of weekend work.
The pressure really built up when i started going college, i lived about 7 odd miles away and with our useless bus service, it was just as quick on a pushbike . My parents gave me no money to fund my college expenses, so i paid for my own food, the cost of a £400 bike, a new computer, college fees etc. I also had to pay my way for my own luxury items and going out money. Managed all this on about £45 a week, it was always a push and i'd often go without eating at college.
I still got by and really do thank my parents for it, i didn't realise how independent i had grown to most my friends. I also found moving away a piece of *****, and no trouble at all.