Could well be a case of finding the correct Halfords. For instance, my local seems to employ scruffy, uninterested teenagers that mumble and stare at the floor. I've heard of some dodgy setups at various Halfords too.
Anyway, not to bash 'em too hard. I'm sure a Halfords is only as good as the people that work there. Point is, if you find one staffed by people that care/know about bikes and personally invest in your best interests, it could turn out fine. Best to go in, have a chat and gauge who you're likely to be dealing with.