Good Afternoon Squib, thanks for your post on our Community Forums and a very warm welcome to you!
Sorry to see this has been left unanswered for an extended period of time, or have you been able to change the phone number?
You wouldn't need to do anything in regards to your contacts - if they're saved to your handset (which is my personal preference) then any SIM card could be placed in the handset without the numbers being removed
The other option is to save the contacts to your SIM card, which would be an issue if you have a former EE Hosted SIM card (which is red in appearance)
If you have a new Virgin Media Controlled SIM card (purple in appearance) we wouldn't need to change the SIM card, and this therefore wouldn't cause a problem either
Kindest regards,
David_Bn