We are spending only three nights in London on our way to Paris. I am a little less interested in big cities, and would like to get out at least once. Beachy Head looks great, and I'd love to get photos of the 7 sisters around sunset and walk along the cliffs if possible. We will only be using public transportation, but it's hard to figure out how much of one day we would realistically need to devote to this excursion (including travel). Perhaps it is an unreasonable wish.
Any advice/suggestions/tips?