Becoming an Air Ambulance pilot - am I dreaming?
Well, I wouldnt attempt to provide an answer to your question or advice, not being employed as a commercial pilot. However I can offer a concrete example of a friend who did this in the U.S., but starting from a somewhat different point. He was in his early forties, with a CFI-airplane when he began flying helicopters. About 3000 hours in airplanes, but not working as a flight instructor, and not flying for a living at the time. Began flying helicopters and decided to pursue it as a career. Did a PPC, CPC, CFI, and CFII working at it full time and flying as an instructor at a small helicopter training school. Over two + years, accumulated a little over 1000 hours, did the ATP, bought a little turbine time (not a lot. more like 25 hours) and got hired by one of the larger EMS operators. After two years there, got recruited to fly EMS for one of the more prestigious hospitals in the U.S. at somewhere around age 45-46.
So, it can be done later in life, but the outcome will depend heavily on one's motivation, skills, and ability to build time quickly and check off the ratings. Will this work for you? You are probably the one best equipped to answer this question.