This thread is hilarious, but in all seriousness to the OP, it can often be a little nastier than people are making out here.
There is plenty of banter, which if you are British, I just think you have to put up with a little bit if you are going to make friends outside of your own area!
However, I do think there is a core of people who are actually quite serious. I am a southerner who speaks 'RP' but has spent time living in the north, and I have plenty of friends who banter about my fridgid southerness (though I can drink 
) and we have a laugh and I moderate my po-faced'ness!
However, I have also met people for whom it became apparant fairly quickly that the banter was actually masking a fairly serious belief that I was somehow inferior due to the fact that it was obvious to them that I and no-one else in my family had ever worked a day in their life due to being bedecked with priviledge from the moment of conception and were therefore responsible for everything that had ever gone wrong in their own lives and families, and the lives of all of their ancestors back to Abraham.
Like a mumsnet competitive poverty/anti 'rich' people thread on acid.
I do come from a relatively comfortable background, but most often these people did too, and I have to say that really, really grated.
Plus in my experience (London-based) it is not true that southerners hold equally narrow views. The only time I ever experienced a person sneering about 'northern birds' was a bunch of rugger buggers at the pub, which as I am sure you are aware is by no means representative .