Skimbleshanks,
Credit scoring isn't set in stone - 2 lenders could access the same persons credit file and get different scores. A person with a clean credit file (on the electoral roll, no arrears, no ccjs etc) will get a high score from a lender that wants that type of customer. The same person would get a low score with a lender looking for someone in debt / with ccjs / in arrears etc. In a nutshell, the credit company supplies the raw data and the lender decides on the score using their own criteria. No-one has a specific score as such.
Updates - electoral roll is once a year, all credit cards / loans / mortgages etc (any type of credit) is updated once a month. CCJs, property reposession, hits on the fraud registers are updated as when they happen.
Anyhow, if you trade for a living getting credit from the high street / big name lenders will be a problem. The info the credit agencies provide won't be the issue - it's how the lenders use it. The self cert mortgage route mentioned in the last post is a good idea (make sure you have at least a month for filling in paperwork!)
Stakka