The question is not what skill you have, but if you can make something a little innovative or novel. I am self taught and don't do it for any reward, but, some of the things I make are not generally available, I am never short of people looking for me to make things for them. I have received offers for doing stuff, which would if I started to take them up enable me to make a very reasonable living.
Whilst not doing it for a loin, I would focus on creating a really good workshop whilst you have the time to buy machines and kit at opportunity prices. Focus on buying secondhand really good kit, there are in my experience few 'joiners' with a proper workshop. As a consequence this type of work can pay more than 'fitting'.
Making standard windows and doors, stairs, etc, would enable you to make a living, however there is a lot of competition. If you know or are someone very creative, there is an opportunity to make serious money. I read a while ago about a lady with a fret saw who started making Christmas decorative items and now employs 10's of people living the high life.