Alternatively apply for a 20 month career break (you can have up to 36 months). This way you can sod off sharpish (career breaks can be sorted in fairly short order) start the civvy employment and then if it is all tickety boo whack your notice whilst on the career break. Do this before the 8 month point and you can work your 12 months notice on the career break.
It works and these days career breaks are quite common as they are a good retention measure (ha ha ha). Just convince your boss you want a career break and he should submit a request to your career manager / desk officer.
Easy, and it gives you that fall back option for when the economy goes tits up and people are laid off (heaven forbid).
Cheers MFWF
