There are some good things about living in Turkey and also some bad things. You just have to balance it out. This is not paradise but then again where is? You get quality of life from what you make of it and its not really down to location.
Also you should really ask what your kids want. My father moved around a lot when I was little and every time he moved it was losing all your friends and having to find new ones and has a kid, I didnt like it. Also you should seriously consider their education, a state school in Turkey is of no comparison to a school in the UK. I have seen many many families move back to the UK just because of this. What you do now effects your kids for the rest of their lives so seriously consider what you, your husband and the children want to do.
Also does it have to be Fethiye? Your husband may get much better job prospects and benefits if he worked here in Istanbul or in Izmir. He then wouldnt have to rely on seasonal work.
Even if he doesnt have a trade, I know that big corporations here in Istanbul are screaming out for English speaking chauffeurs to drive executives around and could earn over 2000 lira per month or more and get benefits that include health insurance for the whole family etc.
IMHO I would stay and at least wait till the kids have finished their education to give them a head start in life and if you have a son, then at least he can choose on if he wants to do military service or not whereas if he was in Turkey then he wouldnt have that choice.