I'm in London. I agree with OP that cunt is the most offensive sayable swear word in this part of the UK (which happens to have a population greater than Scotland). I find it incredibly misogynistic. I don't tend to swear anyway. Other things I find sexist:
A woman is called a bitch but man (esp in America) is called a son of a bitch. The insult is levelled at the man's mother, not the man.
A man may be called a bastard - ie that he is the product of an unmarried mother. The insult, again, is not at the man himself but at his mother.
I disagree that sexual coarse language is taboo language in this country, though. I have spelt out the above words in full and do not expect to get banned from Mumsnet.
The most taboo language in the UK is racist language, ie n and p**.
The oh-so-shocking and offensive comedians of our age would never use these words in their shows and if they did the BBC would fire them immediately. The middle-class mummies who find it cute when their seven-year-old child writes 'fuck' in context in a homework assignment might find it less cute when their child uses 'n***' as a term of endearment for their classmate.
So I'm afraid I don't buy into this idea that all language is acceptable and we have reached a stage where we have evolved beyond taboo words and only pearl-clutching Daily Mail readers could possibly complain. There are always taboo words - they just change over time.
Right now racist language is (rightly) outlawed in polite society.
Sexist and sexual language is cute and edgy and very much 'in'.