Good luck to them but I can't see where they will attract more passengers from than already use the airport.
The SE is well catered for by existing facilities which are far more competitive than Lydd ever could be.
Freight is an interesting proposition though, a much longer runway than that proposed is required - 2000m + to cater for the sort of freight a/c which are the realistic market - given the concentration on passengers by local competing airports freight could be Lydd's saviour, but they only have one chance to get it right.