American English vs British English, Part One

A field of rapeseed. Erm…. What?!?

I am sure American vs British English will be an ongoing topic, but we'll start with this item. 

Every day I walk into stores and am immediately welcomed with a smile and then, the dreaded, "Hi ya, you all right?" Sometimes they add one more word to make it "You all right, there?" 

Gosh. I don't know, should I not be all right? Am I bleeding or something? Should I be standing here, or should I be standing over there? If I'm in someone's way, the proper British thing to say would be "Sorry," (not excuse me — as that would indicate I have a question, or pardon me — as that would indicate I had just burped or farted) but I really don't quite know what to say.

I learned shortly after moving to England that "You all right, there?" is equivalent to "How are you?" in America. However, while it's easy for me to reply to the American version with "I'm fine, how are you," for two years I have awkwardly handled the British version of the question. Replying "I'm all right. Are you all right?" makes me feel like I should feel their forehead to see if they're clammy or feverish and in need of a doctor. 

I have asked some of my new British friends and they just say I should reply to the query with "Yeah, you?" But even that feels awkward for some reason. 

Oh, the stress I put on myself for no reason whatsoever!!