Have you seen this? I haven't used it myself but it looks interesting.
The Isle of Wight appears to be keen to encourage dog owners to vist. This is a useful holiday destination as dogs obviously do not need a pet passport. Wightlink, the company that owns the ferries between the mainland and the island, not only provides free ferry travel for dogs but has produced a guide to dog friendly places on the island:
http://www.wightlink.co.uk/isle-of-wight-guide-and-events/walking/pawprint.