This bothers me more than most people, because I like playing brass instruments. Every now and then, that involves putting a bit of pressure on the teeth. A few years back my dentist turned me on to Sensodyne toothpaste. Can you get that in the U.K.? If not, let me know and I'll look up what the de-sensitizing ingredient in Sensodyne is, and you can find an equivalent brand. My advice: avoid the baking powder (or do I mean baking soda? I always get those mixed up!) brands - they taste disgusting!
Sensodyne's alright, though. I brush with it all the time, and I even got really used to the taste, so I brush for a long time, sometimes just sucking on the brush for a half-hour or so. Weird, huh? But with that and the water, I have never had a complaint from the ladies! And my teeth stay numb, which is the way they oughta be.