It depends on the lifestyle you would like to lead. The expenses to consider are residency and compulsory health insurance. Residency is about a pound a day,health insurance is compulsory now,think it is about 182 lira a month and who knows what it actually covers.I do not know if that will cover the dentist as well. Meat,petrol and some foods that you take for granted in Britain like Cheddar cheese, sausages,bacon cost more in Turkey.If you are going to pay for maintenance on an apartment the cost of that should be considered too. If you run a pool of your own then chemicals and running costs of that have to budgeted for.
You need to check your finances well before making a decision like this.The exchange rate on you money and the interest on the money you may put in a Turkish bank are not predictable.