Today is a momentous day in parliament. The currency markets hate uncertainty, and that is entirely the situation!
Interbank rate at 12:45 BST is 1.1. TravelFX rate is 1.08 for cash. Tesco (on line purchase) 1.076.
Probably, most people will have been and gone by now, but those who haven't have to gamble on a rate increase. This seems pretty unlikely, although it may improve if parliament succeeds in blocking a no-deal Brexit. But that may trigger an election, in which case the pound may go lower still.
By mid-October it becomes fairly academic in terms of holiday money for trips to Agios Stefanos, since the season will be over. For next year there will probably be some kind of deal made,and the pound will probably rise.