if the natwest do freeze my account before my wages go in what happens to the money? Does it bounce back to the employer or will it get deposited and i lose it?
it gets frozen until the OR states he has no interest in the account. Then it is the banks decision, you should avoid it going into an account that is likely to be frozen.
It is ok for your salary to be paid into a 3rd party account as long as you inform the OR and explain that you are doing so to avoid having no money to live on rather than redirecting funds away from the OR and your creditors.
I think each bank is different, some will hold the money and just pay the essential direct debits, you wont be allowed access to it- such as Coventry Building society where as some will bounce it such as LloydsTSB.
You should check with Natwest or RBS to see what their policy is