Big Al's right, the first year NVQ1 is basics, the second year NVQ2 is more advanced....and if you're any good and get your head down, you can complete 1 & 2 in one year. NVQ3 is more about taking a supervisory role which if you're gonna go out on your own is fairly pointless. Skills wise, you won't really learn much more in year 3. Some firms will take on 30 year olds if you're keen enough. There always a pain in the arse 19 year old who's more interested in souping up his Nissan Micra for firm's to get rid of if you're keen enough.
If you're paying your own way & not working for a firm, you'll be awarded an ICA (Intermediate Construction Award) and an ACA (Advanced.....) if you do year 3. You can convert these to the full NVQ at a later stage if you find employment.....but presumably it's the skills you want rather than a piece of paper ?
At the end of the day, regardless of whether you have NVQ level 1, 2, 3 or a degree in timber science.......any employer will put you on a trial period. If you're good, quick and don't f@*k up then you'll get the job rgardless of your qualifications.
If you're not in joinery employment, it'll be tough to convert the college based ICA/ACA to the full NVQ. Yes, you can take pictures of all your restoration & joinery work, but unfortunately you have to be in the piccies yourself !!! It's also difficult to get old work you've done assessed by a qualified person that way.
I do know of some people (present company excluded of course!), that get a job with their mate's firm just for a couple of weeks or long enough to have the assessor down to watch him making radiator covers or whatever, just to turn the ICA/ACA into the full NVQ....then carry on working themselves as a sole trader.
Don't worry about the age thing. I'm 74 and my missus is 23.....!