Pretty sure the structure is the Menai Bridge, as it fits with the route taken (first town is Bangor), tho not sure what the literary connection is. The Australian Prime Minister is William Morris Hughes.
Identifying the route this week was fairly straightforward with great precision in all measurements and you are probably right is identifying the structure as Telford's Menai Bridge. I don't get the bibulous bit though. Did Telford have a reputation as a drinker? He, apparently, was very congenial company, but Chablis....never!!