If I use the option to block international calls, will that also block calls from friends calling from abroad on UK mobiles?
@Aleko Welcome to the community and thanks for the question. No, it will only block the call if the number has an international dialling code.
Strictly speaking it will only block international calls if the call message has an international flag setting, i.e passed through the international gateways. Many scam callers spoof numbers beginning with 00, which can still show on a caller display.