I was in a similar position nlp and if 67 is your birthyear, we are of similar age.
I have been in the same job for nearly 27 years but can retire at 50 ( hopefully) on a pension.
I have dabbled part- time in electrics for years but was nothing more than a labourer, so I decided to get my " tickets".
I went to College one day a week for three years and have just passed Level 3 2330 City and Guilds.
I only did it to have something to go to when I retire to earn a few quid but have found that I am now very interested in the subject.
I thouroughly enjoyed the course(s).
If you know the building side and can handle tools you should ( in my opinion) get as much experience on site with whoever you can and run your college stuff alongside.
You'll have to work as well.
I studied Commercial/ Industrial/ Domestic at College but will stick with Domestic stuff as it is what I know. But the other knowledge may not be wasted, who knows!
If you want to do domestic stuff then you can take quicker routes with much shorter courses and then join a "body" NICEIC, Knapit, Elecsa etc.
This allows you you to sign off you own work.
So, it doesn't really matter how much work I get at the moment, but I pick up bits and pieces.
The full time Sparks I know in London are really struggling.
For a change from your current job into a Sparks will take time and will cost YOU money so think twice!
I mix with many different trades and the only ones who are really earning good money are Heating Engineers (GSR ones)
If you have any background in plumbing I might suggest that route.
Ironically, there is much less to learn and much less "red tape"
If you need any help in any way, pm me, I will try to help.
All the best
Gerry