It seems, quite justifiably, that the garden at Prospect Cottage is a dream destination for many gardeners but likely to remain on many wish-lists because of the distance involved in travelling and the logistics of overnight accommodation. I can possibly offer a solution.
By chance, I mentioned to my sister (who lives in the Midlands) that I was going to Dungeness. "Oh! I've been there; that's the place with those funny little cottages at the end of the railway line." Er, yep. That's the one. You need to know that my sister is not interested in gardens, neither is she likely to suddenly take off to the south coast on a whim, so I asked how she came to be in Dungeness. She had wanted to find a means of enabling our extensive family to visit my lovely niece who lives in Kent and had booked a Sun Holiday (the cheap £9.50 per person variety) at a holiday park in Dymchurch. As a means to an end, she thought the weekend spent in a seaside holiday caravan (self-catering) was not too arduous, despite the weather being typically out-of-season dreadful. She hadn't known about the existence of Prospect Cottage but took a trip on the Dymchurch to Dungeness steam railway as a treat for her little grandson.
So, while it may not be to everyone's taste, if you want a cheap way of visiting Prospect Cottage, it may be worth your while to book a weekend caravan at Park Holidays New Beach and let the train take the strain. Once you arrive in Dungeness, the Britannia Inn serves delicious fish and chips and there are other local attractions such as the 'acoustic ears' and lighthouse to visit.
I think the Sun Holidays offer comes round about three times a year but is cheapest in the Spring and Autumn - I'm not a Sun reader but I know a man who is!
(Not drowning, but waving…)
One of Derek Jarman's stone circles in front of Prospect Cottage.