I think it depends on the percentage of the house price you are borrowing. eg if you're borrowing 95%, the lender will probably want some action taken. If you're only borrowing say 60% they might not be so bothered.
But It's a while since I moved house, and I think there have been a number of rule changes.
If there are any problems, and I hope there aren't, you can always try and offset some of the costs by going back to the vendor and suggesting a "reduced price due to the findings of the survey"
Just spoken to them, it's not a condition that it is done for the mortgage, just what the surveyor reccommended due to the age of the property, phew thats a relief i had an ominous feeling of being more skint than expected.