What A/c Type do you want to do this on? Alpha Aviation and Jetflight Training are good. Check STD DOC 24 and LASORS for the requirements. CAA will accept some types as " common" for TRI for instance 30 sectors 752 in the past 12 months would meet the requirement for a 737 300-900 TRI , but 767 would not and A340 time may not allow you A320 TRI. Don't forget you will need to do a core " teaching and learning" course prior to the TRI if you are not instructing at the moment.