As the following link shows, Be Broadband are trialling landlines for customers - proposing 3 tiers of service:
1) Broadband only landline (no outgoing calls)
2) Evening & Weekend calls (Broadband included)
3) Anytime calls (Broadband included)

Trial starting with 70 customers only, but intends to save customers money compared to BT.

Link to some information: http://www.techradar.com/news/phone-...ndlines-700557

If the prices are good, then I may look into it. I'm already on Be Broadband.