I unlocked them using the Windows CMD line (put the phone in USB debug)
Then I downloaded the 2 files you need from here http://forum.xda-dev...ad.php?t=846913
- I9000XFJS2 (Stock UK 2.2 ROM)
- ODIN + PIT
It was all very straight forward to get a Stock ROM on
It also looks Very easy to use ODIN to put on Custom ROMS (plenty of Gingerbread ROMS)
Basically there seems to be little about this on the MoDaCo forums.
But as XDA has so much going on I am reluctant to post a full guide here as - the XDA content is very good - and I don't actually own a Galaxy S.