I don't need anything expensive as it'll be just for my bike, looking around there's a makita 48 piece socket set for £22, no point in spending £150 at halfords as it'll be a waste of money.
What size? If it's a flimsy 1/4" drive set then it will be of limited use. Ideally you want a set that includes at least 1/2" and 1/4" drives which should cover most situations.
It's hard to beat the value of the Halfords Pro sets when they are on offer.