First aid courses
Really out of date I know but I have qualified in the adjuncts, defib, spinal etc that you were talking about. Speak to Dave Whelan (Will) at The Training Centre, Lusty Glaze, Newquay, Cornwall 01637 876631. They run first aid courses from one day appointed to EMT-B (first response) as well as lots of bolt ons. I've been instructing for them on an adhoc basis for a couple of years and the work is quite regular and well paid. They are always looking for locum instructors all over the country if that is what you are after (they may be able to give you advice on how to start your own firm doing that type of thing but I doubt it!)
I know from my own experience that there is a good market for that type of thing but it is fairly specialised and you'd have to pitch the price right. I was instructing O2, defib and spinal management to the Dev&Corn det officers which might be a good start point in your force area. Go for it, and if you need instructors give me a call!