My broadband at the new flat is £23 a month for unlimited Fibre Plus broadband (up to 76Mbps/average 63 Mbps - I was getting 50/53Mbps last night when downloading Windows Updates on a laptop I'm fixing).
It's tied in with a dual-fuel tarrif, and having all three reduces both the gas and electric prices by 5% as well.
Calls are charged seperately, but you can add unlimited UK landlines/mobiles Evening/Weekend for £5, or anytime for £10 (or £12 if you want to include international calls).
So I don't think I'll be taking the BT. EDIT- One year later than this post, when my fixed tarrif at the energy company ended, I did switch to BT.
PS. My mobile's gone back onto a £1 a week PAYG pack which gives 100 mins, 200 texts, 10mb data.
(if the 100 mins runs out you just start another pack for £1).