There's some updated info at
www.virginmedia.com/pausesports. Customers who have paused subscriptions will start receiving personalised emails from this Friday explaining when their charging will resume. and any pro-rated charges or criedts that will be applied (it varies depending on your billing date and which channels you subscribe to).
But in short, no you don't need to contact VM.
Edit: I've just watched The One Show. That reference to applying for a 50% discount was for BT customers, not Sky or VM ones.