1) CMT RAMC
2) CMT Unit sponsored
3) Regimental Medic
4) Unit first aider ( or bandies)
5) Patrol medic (SF)
then there are real medics, Navy and now RM (in my day all commando medics were RN, now they have Bootnecks too)
Surgical support teams (nurses, Doctors etc) also suppliment 3 Cdo within the field hospitals (Red and Green Life Machine springs to mind)
The only unit to have CMT trained ranks from within their own is the Patherfinders I believe, Most other CMT are RAMC who have jumped out of planes and run around catterick with an ickle stretcher....oh and spent a few trips to Brecon to fill in Hats in the Wheatsheaf.
If you want to be a medic and see combat try the RM/RN route, you tend to work alone, the training is longer and better and you do have a lot more skills and responsibilities (remember RN medics were intially trained to work alone on a ship without backup) you get to do the commando course and if you go SBS get to jump out of planes and WRENS aswell.
Army medics tend to work in groups, one to hold the box, another to paint it, and a third to fill it with blankets and a stripey medic to tell them to do it all over again.
RAF medics are all gay and spend their lives filing and walking around airfileds in ill shaped berets and puttees.
Look out for patrol medics, they claim to be doctors after a 7 week course and mincing around civvy hospitals shagging nurses, some are good but they are known to operate well beyond their limits and think they are god.
Myself: Well I am qualified as a civvy paramedic, ATLS, ALS, PALS, AMLS, ACLS, ATACC, Offshore / remote area Medic, Tactical Environment Medic (Close Protection), Diver Medic, CP Medical Instructor, PHTLS, Ex RN Medic RM attached, NAEMT Special Ops Div, NAEMT Mil Division and NAEMT international Division, seen the world and prescribed brufen in some rather lovely places!
as for what medics do..well.....everything from routine sick parades in camp for coughs and colds, remote area hearts and minds, major trauma care under fire, adventure training medicine for biffs who cream in bouldering, sexual health, admin (lots of), and when I served with the RM I tended to do alot of stuff in a field aswell, but the MPs told me off so I stopped. In the private world of PMCs I carried a sidearm and a M4 and was a shooter first medic second, also looked after welfare aswell. I have provided medic cover in the rockies, alps, middle east, norway etc etc often alone and 2 years ago i set up and ran a full squadron development (private) to an african country, which included everything you care to think of, medical evac to UK, resupply, helo casevac and all pre deployment training, innoculations. You also do medicals on people wanting to dive, parachute, go SF etc etc. The down side is you are also responsible for hygiene / health and safety. which must be traumatic in the army, and the shit house / cookhouse.
If you go medic go Commando, Airborne or SF, you will get to do lots of things to lots of people with sharps knifes and needles.