Hi Richard,
It can be difficult to moor close to the petrol station near Benson. Two petrol stations I use between Abingdon and Henley are in Wallingford and Pangbourne. Walk to the town in Wallingford and carry straight on past Waitrose and the petrol station is on the right. In Pangbourne the...
There is a petrol station on the A40 just north of Eynsham. It's about as far from the centre of the town as the river is. It's a bit of a trek but now the only one I know of.
Regards
Derry