I have just rang EE for the fourth time and got the fourth different advice. Fortunately this guy knows his shit.
He advised me -
1. He needed to remove my £10 automatic default spend cap on my account that I didn’t know was there - without this I’d have been fucked trying to use my data
2. Text ROAM to 150 before I leave to ensure the data roaming works
3. I will get charged £8 ish for every 0.5 megs of data I use per day (so £16 if I use 501)
4. Text VM OFF to 150 before I leave otherwise any voicemails I get will be charged at high cost
5. He gave me the EE freephone number to use from Turkey
6. He also needed to change one of the other settings in my account to enable me to use data in Turkey.
Glad I persevered and glad I put all 3 tickets on my phone as the kids have different providers. There must be a lot of holiday makers come back from Turkey to huge unexpected mobile phone bills