Hi Geoffrey,
I am not aware of any mortgage providers who will fund a build (others may know of some but it's not usual in Turkey). You have the land in Akbuk (which is the expensive bit!)....if you want to design and build a home through a local reputable builder you can get some quotes and present these to a UK bank for a loan. I don't have much more info I'm afraid except I know it can be done as I am an estate agent and partner in a construction company here and we have built on land owners land which they have financed via loans in the UK.These people all took out two or three smaller loans at key stages in the build (we agreed a payment scheme with them prior to commencing the build and they paid us in a number of payments of their choice). The land is usually the most expensive part so you'd be pleasantly surprised how much (or little!) you have to pay for the build itself.

I hope that some one else on this site might have more experience than me of financing a new build on your own land.
Feel free to keep in touch, if I can be of any further help.
Regards
Sunny Days