Wikipedia reckons the answer to the toll bridges question is 17 in England and 4 in Wales. The list is here:
http://en.wikipedia.o..._toll_bridges#England
Most of these will be recognisable as modern structures erected to the last 50 years - the Severn Bridge and the Humber Bridge perhaps being well-known examples.
It's the ancient ones, of which Dunham appears to be one, that are far more interesting. I don't know Dunham but I do know about Whitchurch and Swinford bridges over the Thames in Oxfordshire and Batheaston bridge over the Avon to the west of Bath. Certainly Whitchurch and Batheaston bridges are major money-spinners for the owners and the tolls are scrupulously collected.
Whitchurch bridge is about to undergo a major refurb soon and the local councils on both sides of the river are making major contingency plans for the traffic chaos expected to be created.