We too were hoping to travel to Dalaman at the same time as you Peter, A1 travel have those dates available it is now £272 per person up from £216 pp last week! It is an Onur air flight. I so wish I had booked it now at the cheaper price as that seems alot to pay (Christmas or not!) Travel republic had some flights too for that date at a similar price, although I have not checked their website today.
Good luck.