Charlie, not sure if I have any air filters left but they are actually a civilian part (same as the trophy) and available, the rubber between the carb and filter was a little harder to find as the military bike used a non-adjustable one. There are several varieties of that air filter with different outlet angles so you just have to get the correct one. I believe one of the UK parts houses has them NOS.
These guys have a stock:
http://www.burtonbikebits.net/triumphtrw.htm
The saddlebag racks and bags are available.
The TRW did come with a tool kit. A small canvas roll with a few wrenches is detailed in the pam and parts manual. I have a much more extensive one that I couldn't identify but it was surplused in the London area. A UK friend identified it as an "enhanced" tool kit that was to be given to the NCO in charge of the bikes.
You'll have to come and have a look, bring the bike too. If you have a 6V battery we should be able to get it up and running.