If Kent Escapes can't make Alicante work one has to wonder if any "bums to the sun" flight from Manston will be worthwhile.
But it would appear they can make PMI and FAO work, both of which like ALC are big holidays destinations, in competition with multiple daily flights at LGW and STN
Personally I think Kent Escapes would be wise to stay away from destinations served heavily by LoCo's - somewere like FUE, DLM or LCA. These are popular charter destinations, but the competition is much less. Although I suspect Kent Escapes will only ever serve destinations served by their parent Seguro from PIK - and if Seguro dont add new destinations, then Kent Escapes wont expand outside of Spain/Portugal