Electrics in '96 Golf

On Monday, the electrics in my '96 1.4 petrol golf went wonky. The cat lights don't work, the central locking wont work, the buzzer to warn about lights left on doesn't work, the clock is reset every time the car starts. When I start the car, I hear a low buzzing sound for 2-3 seconds, this is new.

Any ideas?

Not sure - maybe the immobiliser? I've heard if it starts to go wonky it can result in things like this.