You could also just do the CPL and the IR and then keep it ticking over spending just as much money and time you want to spend. Your could let your IR lapse if that is too expensive to maintain and make do with IMC rating and privileges only for that time, or you could use the annual renewal as a really good brush-up to get you back into shape.
You could even stop flying entirely, save the money, and then use it all in one glorious burst in the end to get back in the saddle.
There really are only two things you have to avoid
1) Letting any rating lapse more than 5 years. SEP/MEP/IR renewal up to 5 years is a not too onerous extensive check flight with any qualified examiner, after that for the IR it is a full IR skill test with a man from the CAA
2) Letting the Class I lapse - check with the CAA how often you need to do it to avoid needing a new initial examination at Gatwick
Presumably, as you like flying, you could just step down to SEP/IMC or SEP/IR and get back in the MEP business... up to you