i am off to turkey for a week in may and not sure what money to take;
1. turkish lira bought over here in uk,
2.travellers chqs to change over there or
3.sterling to change into lira over there?
You will get charged for using an ATM but you will also get charged for exchanging currency and/or travellers cheques so there isn't a great deal of difference.
I have travelled extensively and prefer travellers cheques. Many banks won't charge you to exchange them, those that charge are often cheaper than ATM charges - shop around for the best deals - ATMs incur a charge which you won't know about until long after you've got home. Taking sterling is ok but if you lose it, or have it stolen there's no protection. With travellers cheques they can be replaced.