Thanks all for the replies.
safechav - burtonpower do them for £7

so might get it from them. is the switch just a switch that sits on the wiring for the fan ?
chris - i've got a oil temp gauge i must get round to fitting ... i suppose that would be the wise option
gambit - they're mounted in front of the i/c, did think of moving them to behind it but wouldn't they be blowing air out of the front of the car in that position ? the gauge hasnt gone into the red, just worried that it might.
vroooom ptssssh - pretty sure i dont have the plate on, can see why that would restrict it more.
what about the revotec electronic fan controller ? anyone used it before ?