this bloke at work keeps coming over and chatting to me for ages.

He obviously finds you interesting, otherwise he wouldn't come over and chat with you all the time.

he makes a point of telling me he is single and asks me lots of questions about myself and remembers almost all of it.

Very positive, he wants to impress you, by getting you to talk about yourself, finding out information about you and he remembers it, very impressive.

He tells me he likes my hair and could talk to me for hours.

I do occasionally tell women I work with, I like their hair.  So that feature alone would not tell you he fancies you, but together with the other things you mention, I would say it is pretty conclusive.

I often see him looking over at me. We work in a large store, sometimes he is at the other end to me, but I see him glancing my way.

If I ask you, are there guys that work in the store that you don't find attractive?  And do you look at them a lot?  I don't think you will do!  So I doubt he would stare at you all the time, if he didn't find you attractive.

Do you think he is just being nice or actually fancies me?

By what you have said, he most likely fancied you.

I don't want to ask for his number and make a fool of myself or be the talk of the store?

You need to get to know him a bit more, before you ask for his number.  Your first impressions of him seem to be good, but first impressions are not necessarily right.  Eventually a time will come when you get the chance to ask him out or ask his number. 

But also you could try and tactfully force him into asking you out or asking your number.  For example you could be playing with your mobile at work.  You could say to him, there seems to be a delay in me sending or receiving text messages, my friend sent me one yesterday and I didn't receive it till this morning.  See if he offers to send you a text message to test it out.  If not, then ask him if he can send a text message so you can test your phone out.  You can make up inventive things like this. 

Or he could be talking about what he is doing at the weekend.  He mentions he would like to go and see something at the cinema, you hint to him I fancy seeing that as well.