I'm in a similar position (although older than you judging from your image) I am a C&G 236 (parts I and II) qualified electrician and have never completed an apprenticeship. I never got into this line of work until I was 24 (by which time apprenticeships were pretty much non-existent) I've spent most of my time as a sparks working on commercial/industrial installations. I spent 5yrs at university studying computer science and then spent 5 years in IT and now I can't even bring myself to write a single line of code. I am now teaching myself to make furniture and carve wood. I don't have a mortgage and I have a 9m x 5m workshop at the bottom of my garden and I spend most waking hours in there 'doing stuff' (that's what I tell my wife) and I just love it. It seems to me that the only options to upskill in the furniture making arena is to sign up for a course with the well established furniture makers i.e David Savage, Marc Fish, David Charlesworth, Peter Sefton et-al - they all run various courses over different durations. They are however, expensive (around £18k for a year plus accommodation and travel). It's not an apprenticeship per-se, but you do get a certificate. These people are highly thought of in their field and I think having studied under their tutelage carries a lot of weight when applying for positions within the industry.
I, like you am not interested in domestic/construction carpentry and would dearly love to join an organisation, but I'm 60 next year and I think my ship has sailed ( I would swap it all for a career making furniture in a heartbeat). So I'll just keep teaching myself, watching loads of Youtube stuff and ask questions - you never know - there might be some lunatic out there who needs an older worker still willing to work hard and learn new skills.
Good Luck with your quest
Dno (www.andonart.com)
Great work with the stained glass projects ! do you make the stained glass yourself ? And what about the furniture coming with it ? The snowdrop lamp and the frame mirror look very good (though the picture doesnt do it justice !). I dont think you really need an internship !
Really like the door panels too !