If you've a bike rack on the back make sure you have a diagonal striped 'Long Vehicle' plaque to put behind the bikes, and make absolutely certain that they don't obscure any part of the number plate. We were fined (marched to the bank by an automatic weapon carrying policeman) a huge amount - and needless to say got no receipt!
You should use dipped headlights at all times outside built-up areas, on motorways, mountain passes, and in tunnels, and carry and use a reflective vest if involved in anything necessitating you having to get out of the car at the roadside anywhere outside a built-up area.
