I don't think I've explained myself well.
There is a light switch in the bathroom already (although I plan to change that to a pull cord), but I want to install a light and switch in the loft, that will only work when the light switch in the bathroom is switched on.
Does this make sense, or am I going mad???
Anyway I think the solution may be to get a small flood light and run an extention lead up to the loft when I need light up there!!
Cheers