Did Ottergirl ever get a reply to her pension question (#6532 I think ?)
Presume NAPS is a defined benefit scheme for which I would think you become effectively a 'deferred' pensioner with your entitlement fixed in terms of number of years and salary but adjusted each year in line withe the rules (eg by rpi up to maximum of x% or, if you are luckly, fully indexed). Same as if you left the company. You could transfer out but be very very careful you understand what you are giving up (strong default is to stay put).