It’s in the terms and conditions if you google virgin media broadband terms and conditions / “the legal stuff”, it’s under the cancelling options. Not at home myself so don’t have it to hand.
Post it by recorded delivery, your 30 day notice period to cancel would start the day they sign they have it, even if you don’t hear from them for a week or two to confirm it, little staff and lots of paperwork to get through (I understand you want to cancel immediate either way).
You’ll get send a final bill once the disconnection period is up, that will outlay at early termination fees and stuff you owe them or they owe you. Billing etc all continue as normal while in the disconnection period but if you have already cancelled DD they won’t be taking any more in that period anyway so not to worry.
