In England, 'up north' pronounced 'oop north' refers jocularly to those areas where 'up' is so pronounced, roughly the northern half of the country.

Well, jocularly if you're not from there and it's not therefore your normal pronunciation.

By the way, to me 'uptown' and 'downtown' are only used of American cities, and I've never been clear on what they mean. In London, the downtown part is called the West End, i.e. where most of the theatre and shopping and embassies are. The East End is the traditional home of the Cockneys (and now such groups as Bangladeshis); and between them is the City, the small central business district. And around them is the rest of London; these 'ends' referring only to the innermost part. If you're in London, going 'into town' probably means going into this inner part, and going into the City is more specific.