Yes, you can take out just the Virgin TV & Broadband Package.
That's what I've got and I've never had the Virgin phone.
I still use my BT phone.
It will cost you �30 per month but I pay �25 because I've been with them for years (since the NTL days) and I do my billing by eBill to save on costs.
More info here:
http://allyours.virginmedia.com/
Click on the Bundles Menu Tab.
Also, check your postcode on the same link to see if you are in a cable area.
Customer service isn't the best so keep track of all your invoices and stuff. Query everything.