Have you done a manual search for available networks? Also check your APN settings:
Name — Virgin Media Mobile Internet APN — goto.virginmobile.uk Proxy — Not Set Port — Not Set Username — user Password — Not Set Server — Not Set MMSC — http://mms.virginmobile.co.uk:8002 MMS proxy — 193.030.166.002 MMS port — 8080 MCC — 234 MNC — 30 Authentication type — PAP
Did you setup international roaming for voice and data before leaving the UK? If not there is a help section on the VMobile page that gives some help. I had the same problem recently in Malta when my SIM was changed to 4G and lost my international roaming.
There are 10 types of people: those who understand binary and those who don't and F people out of 10 who do not understand hexadecimal