shops, of all kinds... call centres... anywhere that's looking for staff really.
Start on the floor, work your way up to team leader/supervisor etc
My brother started a plumbing apprenticeship after his GCSEs, didn't like it and left for the army. Didn't like that, came home and started college to do A-levels. Decided that wasn't for him and dropped out. Worked in a few casual jobs then started in a call centre, just on the floor on the phones. He was made team leader and then after a while something else above that. He's happy enough with what he does now and it pays well enough.
Another friend spent 4 or 5 years at college, repeating years, changing courses etc and never actually got a qualification out of it. He started a while ago for some insurance company and worked his way up through that, company car n all that now.