You can also vote by proxy (i.e. authorise someone to vote on your behalf), which might be useful if you are likely to be in hospital or are otherwise too ill. That is described here.

You need to apply for either in good time; normally, registration is done every autumn. I am not sure if it’s still possible to register for the UK election next month (6th May 2010) for example.

Beware of party workers who try to get other people’s votes by signing them up for postal votes and then switching them to proxy votes, which they then cast themselves. This is known as “granny farming” as elderly people in nursing homes were a common victim in past UK elections (particularly the 1992 general).