Do you actually want the currency, or just exposure to the exchange rate (i.e. a derivative). If it's the latter your best bet is spread betting or CFD trading (e.g. IG Index, CMC Markets etc...) - with spread betting you pay no tax, but it's a mugs game.
Unless you are extremely experienced I would stay far far far away from FX, the volumes traded are astronomical, the volatility and market factors (particularly with an EM currency such as TRY) affecting the rates are very tough for inexperienced traders. It's not really something you can just dip your toe into. Your best bet is to set up a dummy account somewhere and see how you get on (for a few months).