Wiring bathroom fan heater

If I could think of a way to get a new cable to it then I would. The bathroom is upstairs and the cable comes up through the floor, nothing else around to spur off. Don't fancy pulling up any floorboards or anything. I'm not an electrician though, so perhaps I might get a second opinion. Any cornish boys here?

 

Thanks for that Owain, I had seen that before but I didn't look at it properly and dismissed it for some reason, but actually that would be ideal and neater.
Now that changeover switch came with no instructions at all, so for a diyer like me, it's not helpful. Basically it's got 4 terminals on the switch with numbers and arrows. There are earth and neutral connectors on the box not part of the switch. There is a small diagram with the configuration jitender posted on page 2. So it looks to me it only switches the live?