You are in a permanent, ongoing contract with VM until you give VM 30 days notice to cancel your VM services. If you are outside your minimum term commitment, you should be able to give 30 days' notice and leave with no early disconnection fees.
If you are in a minimum term period, then VM will charge you early disconnection fees if you terminate your VM services. If you move within the UK to an area outside of VM's network coverage then VM will credit back your EDF upon proof of your new address.
https://www.virginmedia.com/legal/fibre-optic-services-terms-conditions/early-disconnection-fees