Technically no, but it will be a lot harder than if you were in your 20s. It's not just the learning, which gets harder with age, but you'll need to gain experience by working for someone else.
Employers are quite fussy about who they take on, especially people they have to watch and train up. Some take on school leavers as apprentices because they get paid by the government to train them up, some will take on adult trainees but view them as a cheap source of labour (around £10 p/h but could be as low as minimum wage), but few will want someone who is older, less agile, takes longer to learn things, and is keen to go on about how great they were at their last job in a completely unrelated field.
Depending on your previous work history, who you know, rate of learning, confidence, ability to sell yourself etc you could be looking at 10 years before you become suitably proficient at the trade to think about getting a van signwritten, putting an advert in the paper and starting to build up a customer base, by which time you'll be approaching retirement.
