If you are visiting relations over the chrismas period I have found staying on the street or car park close by without a problem.
Usually communicated with the locals explaining your visit, not had a problem before.
As it’s the season of goodwill and cold and dark early with all eating drinking and watching t.v.
Haven’t stayed in whitstable, but the same principle could apply anywhere.
A couple of places pop up on the POI map above, though one looks like its height restricted
Google Maps
Google Maps
john