That's a relief. From your username, it sounds like you're going to need them to do some growing up in... Calm down, I'm just yanking your chain.
If you're serious about joing the RAMC, then you should first look to see if there is a suitable TA AMS unit nearby. However, if you're looking to get your dagger, then RMR will be a good bet: you'll not have much of a chance to work with 3 Cdo Bde in the RAMC (unless you plan on being a GP, 29 (RA) and 59 (RE) Cdos are out) and chances to do the Commando course will be few and far between. P Company and Jumps are easier to get on to (if you think hurting yourself for money is fun!), as we have a Med Regt in the AA Bde. And of course, if you feel Hereford calling, there's always the MSU (although being badged isn't a prerequisite for that).
If any physios hear you suggesting that it's your second choice if your too thick to be a doc, they'll lynch you. However, there are physios serving with both the AA Bde and 3 Cdo Bde, although the Cdo Bde's are RN physios in the Cdo Log Regt's Med Sp Sqn. That said, you won't spend more than a couple of years with the AA Bde at the most: the skills of a physio (or, indeed, an MO) are too valuable to squander on one fmn for your whole career.
So you may need to decide: what's more important to you? Being a Commando? In which case, pehaps you should consider Lympstone. Or being a doc?