I assume you need a "Differences" course? You already hold a 350 type rating donīt you.
JAR-FCL 2.220 app1 says that your AS350 typerating should be endorsed in your licence as "AS350/350B3" but you of course still need "D" check to fly one if you have never flown it before!
Then you only need a review of the flight manual and at least 1 hours differences training with an instructor. There is no need for a FTO or TRTO for "D" training. If you have or know someone that has B3 find an instructor and get the "D" training from him.
But then again you have some different view of JAR regulations in the UK than the rest of JAA world so it may not apply in the UK.
I can actually give you the familiarisation right now! Itīs easy:
Batt on
Fuel pump on
Helicopter on
Fuel pump off.....and you are ready to fly! Loosen the frictions and turn on some radios if you want and have fun
