Do London info call D&D or ARCC Kinloss to raise the alarm?
I don't suppose it really matters who you contact first. Getting the ball rolling towards you is the most important. If you contact London info (do the controllers(?) have radars infront of them?), I am sure they would take details and hand you over to D & D. If you contact D & D first I am sure that they could contact London Info to let them know you have changed frequency. Getting your exact position across will greatly reduce the time taken to find you but whether that would be best done by radar or DF I don't know.
BRL, It would be interesting to know what coverage is like and how accurate the DF is over the Channel and other more remote parts of the the UK.