I think that it all depends on whether you plan to be in Turkey for the foreseeable future. The fluctuation in exchange rates only comes into play if you change sterling to lira when the rate is low (as it has been for a few months)and need to change it back when the rate has risen considerably.
In the meantime, whilst in a ytl monthly account you are earning in the region of 14-15% pa net of tax.
Having said that, I personally would not put all of my eggs in one basket and a balance between money held in the UK and in Turkey offers some security. if you have sold up completely in the UK, and you register in the UK as non-resident, any interest is paid without the deduction of UK tax. It is a bit of a palaver, but seems to work. Cathy