ETME2012, wait and see, you do not have to put your preference in yet, especially as you have not even started training. I dare say you will get to visit a ship or three during training, then you can get a vague idea what it will be like on board and you can then make your own mind up where you want to go.
But there again, although many moons ago, I do not think things will have changed dramatically, after training in Ceres I had Scotland as 1st preference and Plymouth as place to avoid for my part IV training, ended up in Somerset at FONAC. For my 1st Sea Draft I wanted 42's out of Rosyth or a Portsmouth based ship, got a 22 in you guessed it Guzz. You will go where there is need, and if that flies in the face of your preference, tough