A friend of mine has invested in a pair of lightweight aluminium ramps for his motorised chair. They stow easily, and are sufficient to get him into most village pubs. He somewhat drily notes that one or two of the less reputable publicans think having a doorstep means they don't need to accomodate disabled customers and likes watching the look on their faces when the ramps materialise. (-8

With many places, I suspect the trick is to book in advance (or go at a less busy time) and make clear that you want a table with uncluttered wheelchair access door-to-table-to-accessible-loo. I've seen that work with many places like the Michaelhouse Café, Wagamama, the Cambridge Blue since its refit and Brown's as well as my favourite gastropub out in the fens (The Anchor in Sutton Gault). Thinking back, there are many others where it would stand a good chance of working.