I would say fix up the pavers no matter what - if the appraiser feels at risk walking into the property that won't set them in a good frame of mind If you can bodge fill the drive so it looks nice, that might do for the moment.

In the UK the valuations for remortgages are often based on models of sale price data of the area (the sale prices of properties are public data here), and nobody actually visits. IIRC if they do, they just say yes/no to the proposed value which is given to them.