To be honest, reading the information in car magazines, UK owners are not going to get any form of compensation, so if you already have the car, I don't think you have anything to worry about? IT's not going to explode, and the roadtax can't be increased to what it's registered at.
The only thing you need to worry about, is a potential recall, where they could possibly reduce the power output to bring the car inline with the emissions rating it's set at. So am I taking my BiTdi to an Audi dealer anytime soon? No chance!!