Perhaps the rules have changed, but I didn't have to go through the full Cardington route, and was a certified DAS instructor under the affiliation of the "school" I worked for (Bridge
If you are looking for part time work, try contacting some local training schools and see what they say
There are other ways of helping out if you want to "put something back" - there's a charity group that transport blood, riders for health, local air-ambulance fund raising, etc.,