There is a checker on this page, under ‘International and Roaming Charges’
I did have a quick look at some of the counties mentioned, and it’s very expensive and not cost effective to use your phone really.
E.g £5 per mb in cambodia!
I would recommend sticking to Wi-Fi and disabling Data Roaming. Or at least setting a spend cap in My BT to ensure you don’t return to a high bill.
You could also buy a local-prepaid sim card while your there, if your phone is unlocked.
Hope you have a nice trip 😊
Thanks for the reply, I thought it wouldn't be cheap so, as u say, I'll disable roaming and just use wi-fi when available.
@revy32 Don't forget it's not just data that comes with eyewatering charges. Making and answering calls can also be very expensive; sending texts will also come with charges, albeit not at life-threatening levels. If you get a call from home, it make sense not to answer it; instead, text or email the caller to determine why they called.