@PB48
You could check your data apn is correct for O2.
https://community.o2.co.uk/t5/Android-Devices-Samsung-HTC-Sony/Connecting-Android-Phone-to-Data-Serv...
https://community.o2.co.uk/t5/Apple-iOS-Devices-iPhone-iPad/Connecting-iPhone-to-Data-Services/m-p/5...
After that, if still using your Virgin sim, pop into any O2 shop with photo ID to get a free swap to an O2 sim card.
I have no affiliation whatsoever with O2 or any subsidiary companies. Comments posted are entirely of my own opinion. This is not Customer Service so we are unable to help with account specific issues.
Please select the post that helped you best and mark as the solution. This helps other members in resolving their issues faster. Thank you.