for civilian convicions contact your nearest C.R.B office..
for a fee and a six week ( if you are lucky)wait they will give a up to date list of all your bad deeds..
this will not give any details that may be on your 120 or 121 so you will have to see your orderly room staff for that..
Badgermac, you will also need to get a certificate of non conviction from the RMP. You will need to speak to someone at the Service Police Crime Bureau Vetting department for this and they will be able to advise you further. I don't have a number but if you ring 192 they should be able to help.
Not sure if this helps, but if you need one from the civvie plod, search your local plods website for freedom of information and take it from there. I filled out the form, paid a tenner and got it back within 40 days.