Report to AINC with the relevant form (can't remember which) and report your injury to the doc. If it's deemed neccesary there is an Armed Forces Compensation scheme...but you knew that already didn't you?
Or alternatively make yourself look a knobber by going to an ambulance chasing 'lawyer'.
TA Regulations 1978 (Amdt 35), Chapter 8 Part 1 - Disability Allowance (DA). Plenty there to tell you (and your unit) what to do if injured during TA Trg. Part 2 is for Death.
Or...........Ask your PSAO / PSI.