Albeit blatant self promotion of my own company ( being an Admin has its perks, not many, but this is one of them ) try
www.flyastraeus.com and more particularly their associated company 'Bond Aviation Solutions'.
We have a JAA approved TRTO and can rate you on the B737-300 thru 800 series aircraft, with base training taking place on any of Astraeus's fleet.
Nb. TRTO = Type Rated Training Organisation
If interested call: +44 (0) 1293 819 800 - and ask to speak to either Sue Masson, or Mario Fulgoni, or Alison Milborrow.
Hope this helps,
Regards,
Tony