I've had the flu jab for about the last 6 years.I had one very minor reaction about 2 years ago when the NHS were worried about some stronger Avian type flu that caused total unnecessary panic for a while.
I would say the annual jab is well worth having.Like you most people have never had flu but say they have it when it is no more than a sniffle.If you really experience flu, as I have many years ago,you just don't want to get out of bed.It is most debillitating.I recommend it.Having mine this Wednesday.