It is worth weighing up the pros and cons before opting to take a vaccine. This requires unbiased information and an objective viewpoint (or as close to that as one can humanly achieve).
I have personally decided to take the flu vaccine, and I'd recommend it to anyone who can get it (medical grounds notwithstanding).
The reduced risk of getting flu (and reduced intensity if you are unlucky) greatly outweighs the side effects of this vaccine.
I've talked to a lot of people here (mostly on the phone luckily) who have already caught flu or other nasty illnesses.
There is also the natural way - healthy exercise and diet to boost the immune system.
Recommended during a winter epidemic of colds, flu and other bugs.
If you live somewhere warm, I'd recommend keeping fit before visiting the UK or anywhere cold in the winter.