With a credit rating like that you will not get a mortgage from any normal lender, only one that charges astronomical rates. A mortgage is a loan on a property or to buy a property and based on your earnings, you are unlikely to be able to get a mortgage large enough to buy a house/flat anyway.
Speak to the CAB or one of the Debt Management Companies, they will be the best people to advice you.
In answer to your other question, Payment Protection Insurance (or whatever it is called) doesn't usually pay out if you work less hours. Unfortunately I was in the same situation last year, got made redundant and was working temporarily for an agency for loads less. I couldn't claim on my loan / card protector insurance and came to the conclusion I would have been better off signing on and getting my debts paid :-(