There is always the 'Bouncer's Charter' (as I called it). Basically, a form of permission from your Stn Cdr which allows you to take on extra paid part-time work in your own time, as long as it doesn't clash with Service requirements. Approvals are, if I recall correctly, reviewed annually.
Originally it was intended to allow those in lower ranks to do a bit of 'controlled moonlighting' such as being a 'security assistant' at a local pub, perhaps. But nothing prevents the scheme applying to officers or SNCOs....
Thus during Resettlement Leave, Terminal Leave and accrued Annual Leave, you will probably have quite a lot of 'own time' in which to do such part-time work. Say your approval is due to expire in Sep 2008 - but you are due to start all your leave in April 2008, with an exit date of Aug 2008.... There'll be plenty of time for you to do such paid 'part-time' work for 3 months whilst still being paid by HM - all legal and above board, but you MUST declare it to HMRC, of course.