If he's really serious about Plumbing and Heating it will show in his work. Get him on a full-time course and tell him to knuckle down and produce his best. If he's in the top 3 he will have a good chance of getting a proper 4 year apprenticeship. That's how I got my last 2 apprentices, one is now a fully qualified installer with more than the basic knowledge of plumbing and heating he's been with me for 5 years, the other is 6months into his apprenticeship. As said if his serious and willing to graft then he will do alright.
Mike
Mike