Thanks for your input, sorry I've been on holiday so haven't had a chance to reply.
Glenn,
Currently I'm doing mostly off-road events: LDWA challenge walks/runs (30->60 miles),Mountain Marathons etc, I did a Bob Graham in July (72 miles, 28000ft ascent), and am down for the London to Brighton in Oct.
Pizza Man,
The weather conditions are my main concern.
How hot is it in Sept. in Greece ?