It's possible, but not as easy as you'd imagine. The mob you're with doesn't have to let you transfer, as that's what you signed up to do. If they do let you transfer it can take over a year, sometimes longer from what I've heard.
Also they'd ask the question "why did you join up as an xxxxx, when you wanted to be a stretcher bearer?"
They'd also ask "What's wrong with being an xxxxxx.....do you not like our corps/regt?"
Ive got the same problem... Im going in on the 4th of august to train as an avionics technician, however i did want to go artillery.
When i did selection i was 3 seconds away from passing for artillery, however, i did pass for REME. I was told i could be put into basic 3 weeks earlier to boost my fitness in order to gain entry for artillery, but when i asked about this they told me not to bother because there are much better prospects as a technician and because of my GCSE and FE results they say it will suit me better!!
Im not as keen on this job choice and have been told id be waiting until next year for artillery!
What should i do guys???