Wether using the "mat" type of electric heating or the "tube" type carrying heated fluid, I found that it's not for the faint of heart when it comes to price
and installation. Themat type, at least here in the U.S. runs about $10 to $15 per
square foot and the tube tupe isn't a lot less. Both are demanding to install properly. If you're hiring it done assure the installer has experience doing them. The mat type uses low voltage electricity and the connectors are small and somewhat delicate. In fact most have at least two connectors in case one is damaged during installation. The tube type can be more difficult to install due to all of the components (here's one type
http://www.nu-heat.co.uk/s.nl/it.I/id.7/.f?sc= 7&category=4 ). They can add a great deal of comfort, especially if installing tile floors in chilly bathrooms, but one has to evaluate the need and cost... in my opinion...