Not sure how these would work around UK light switches – I guess it depends on your fittings. But if they do work, these Building Brick Light Switch Plates will definitely brighten up a dull household essential.
Yes, you can replace your existing light surrounds (or get an electrician to do it), replacing it with a plate that works as a base for a variety of toy bricks, but perhaps most significantly, your Lego bricks. Which means you can build on these, stick your creations on these and generally make the 18 square inches your own. You can even stick a Minifigure or two on there to keep guard of the switch!
It requires a screwdriver and four screws to replace your current plate (and as we mentioned, someone comfortable working with this kind of thing), with the brick plates selling for $9.99 each from ThinkGeek, which sells and ships worldwide.