We've sorted an account out at HSBC in Fethiye via the international banking service here.
This is only for existing HSBC customers and there is a hefty charge, but it means it's all done and our ATM cards and paperwork (in English) will be ready for me to collect when I'm over in February.
The default unless otherwise requested is two accounts - one in sterling, one in Turkish lira.
We didn't apply for a credit card but could have done, and they would have then obtained Turkish tax numbers for us as part of the service. (Not needed for opening an account in this way.)
It took a phone calm of about 40 minutes and an appointment in our UK branch of around the same to do the signature and ID verification stuff.
It does cost £100 but it's easy and convenient and means we're set up in advance.
I've been very impressed with the service, which is more than I can say for our Business Banking manager at the moment. Been trying to open a new account with him since the start of December.