You might like to try www.1944airborne.com - Soldier of Fortune - Yeah I know it's a "Walt" site, but they stock ammo boots in good condition (ex-Guards I believe) and you can buy on-line OR over the phone for next day delivery. Got mine from them and they are in good nick, just need a little bulling.
Get a nice pair of dms from an army surplus store 5-10 quid, you can get the soles and segs put on at any good cobblers for 20 quid and then its up to you to get them to the standard you want, plenty of beeswax and polish and bobs your mothers brother.
Whilst on the subject of boots, does every unit have their own preferences as what can be used for parade boots?
I have a pair of assault boots that I have been working on however I can not get the polish to stop cracking just above the toe cap every time I move!!
I know that a lot of people talk about ammo boots, I have seen a few pairs knocking about and they look good and the makeup of them looks like they will be easier to bring up to a good standard after beeswaxing etc.
i sell ammo boots, i burn them down beeswax em and bull them to high standards. i will try get them in your size if requested and if need be you can send me your boots to be done. so if you would like to enquire please drop me an email at email@example.com
if you would like some pics of some boots that i have done just drop me an email