Not sure you could do the Steyning line now as the bridges were knocked down and there are new buildings all around where the line / junction used to come into Shoreham.
When I was a kid there were weekend services direct to Exeter during the summer holidays which we used to get down to...
Driven past loads of times but didn't realise the old platform was still there until I saw something online the other day. Will park up and have a look around next time I'm passing.