How do you clean a kettle?

[Serendippy]

I normally boil it with a bit of water and some bicarb of soda but there is really stubborn limescale. I saw on a thread that you can use white vinegar but not sure how to do this. Or should I splash out and buy some kettle descaler?
TIA

Killrock is fantastic! But yes, it is forking out for a descaler (but not too expensive). I also have a small thing that looks like a scourer that stays in the kettle and slows the build up of limescale.

WHite vinegar works a treat. I pour a good glug in and some water until it covers the element, then boil and leave. To get rid of the taste fill and boil, empty etc about 3 times.

Citric acid is the best and much better than bicarb. I put a couple of teaspoons in, boil, rinse and boil with fresh water, rinse and boil with fresh water again. Should be nice and clean :). You can get it from the baby section in boots as its used for cleaning steam sterilisers or can pick up larger bags on ebay quite cheap.

I just use lemon juice - you wont get enough juice from a fresh lemon so i use a large bottle of lemon juice from tesco. Pour in a good amount and switch kettel on - watch it froth up and when its done the limescale should fly off!