Wicker, you must be joking. £26,000 for an FI rating and CPL?
That sounds way off the mark. I did my FI for about 10,000 EUR and the ATPLs are about 4,000. You don't have to get the CPL rating although I fail to see the point of not having one if you want to instruct. You can't legally get paid and it really takes alot of time, so doing it for charity isn't an option me thinks. Besides if you're over 40 you could likely land a full time instructing job and make a living off it, most schools have an issue with FIs taking off for greener pastures as soon as someone mentions "jet"...
I'm nigh on 40 myself and just did my FI, with 700 hrs in the book, and I see it as my next career. It's alot of fun, but you need the money to keep it that way.