Most local colleges do courses in furniture making, although they tend to be day release type affairs and at a fairly basic level.
Personally, I wouldn't bother.
What I would do in your situation is visit as many small cabinetmakers as you can in your area and get chatting. 'Networking', I think they call it. Do not write letters, do not phone - its a total waste of time. Call round.
Once you have developed a rapport, maybe even after a couple of visits just chatting about woodworking, offer your services to help out with any menial jobs on a casual cash in hand basis. Half of my time is spent sanding wood when I could be doing something more profitable, and I would welcome having someone to call on to help out as and when needed for a few quid an hour.
This is how things start. Prove yourself as a personable, able, and reliable bloke and pretty soon you will make yourself indispensible to someone.
Another possibility is kitchen fitting. Even in these straightened times kitchen companies are crying out for half decent fitters. Is this something you can do with your current skills?
Don't worry about qualifications or references. As JonnyD says, most small firms are more interested in your personality and ability. Age is actually on your side. As you are 40+ people will assume that you have plenty of experience. You will need your own van and tools, though.
Blag it. You'll soon get found out if you're crap!
Cheers
Dan
