Hi Simon. The authorised dealer for Gulfstream in the UK is Oakwell Motorhomes in Barnsly Tel No 01226 293300. You should also check out the RV goods and services pages of ARVM magazine which if you are not aware is the main RV mag in the UK and an invaluable source of information. You can subscribe on line.
Best regards and happy rving.
Ps if you are in Scotland we would be happy to to see you visit us at M-Line Rv in Alloa near Stirling www.m-linerv.co.uk