This is the only link I could find that looked even remotely helpful. It would appear that just about everyone and their brother in the UK is into WWI and WWII reenactment, but the trend seems to run toward infantry as one might guess.
http://www.regiments.org/regiments/uk/corps/RAMC.htm
Perhaps you can enlighten me. I understand military reenactment. How does one do medical reenactment, though? Seems you'd be at something of a loss for bullet and shrapnel wounds.