Folkestone is seriously underpriced at present and 250k will go a long way down here. The west end is the posher bit but a 4/5 bedder with a sea view here come at a premium. East cliff has some nice places though again if you want to look out at the French coast you'll struggle to find anyhing under 350k - still huge value for money - omg - I sound like an agent!
Your second question is something we'd all like to know but the pundits are saying prices are expected to rocket in the next 5 years? Best come and have a look. Good luck