Hi, I'm was in the same boat as you a year ago, I was 26 then and working in security, it was nice getting to read lots of books and watch DVDs whilst getting paid but I did feel like I was waiting to die! and with a family on the way the hours and wages weren't conducive with the life I wanted/still want for us.
I did a lot of research and found you can do these 4 or 5 week courses but no one will respect you for it and you won't actually know what your doing at the end of it, if you had an endless amount of money to spend it would be a s*** hot introduction, you typically get your 17th edition, 2392 (introduction to inspection and testing) and some sort of part p qualification
what you need really (IMO) is you City and Guilds 2330, level 2 and 3 (will take you 2 years part time and cost around £1600 pa) your NVQ level 3 (should take a year but could be less, you will need a work placement or job for this) 17th edition certificate (3 or 4 days if you do a course, approx £450) and an inspection and testing certificate (was 2391, now something else!) + books and basic tools. That will get you JIB registered as a fully qualified spark and JIB is what matters nowadays it seems.
you can do some of these concurrently and save a bit of time but realistically your looking at 3 years.
I'm a year in with my C&G 2330 level 2 and 17th edition done so far, just waiting for level 3 course to start. I love it but its hard going, next course will cost me £235 a month for 6 months and when I do start work I won't earn a good wage for a while, so my advice would be, do it! but only if your really committed!
Best of luck
Sam