The Time Capsule will need to be located several rooms away from your Virgin router...... in the area where you need additional WiFi coverage.......and then the Time Capsule must connect back to your Virgin router using a permanent, wired Ethernet cable connection.
Ethernet cabling can be run up to about 325 feet, or about 100 meters, with virtually no loss.
Once the Time Capsule is relocated to the area where it will be used, it will need to be reconfigured to provide a wireless network signal that uses the exact same name and password as your Virgin wireless.
If you are able to locate the Time Capsule where it will be needed, post back for additional details on the setup of the Time Capsule.