Withdrawing from ATMs on specific credit cards gets you top rate*. These cards are Barclaycard Travel Card, Halifax Clarity, and Santander Zero (but you need to be a current account holder with them). Of these the Barclaycard because it does not charge interest on non-sterling withdrawals.
* if you took out lira yesterday with one of these cards you would have got £1 = 5.73/5.74 TL.