I know you can get free connection with BT and this offer has been running for a while, however you have to sign up to a 18 Month contract, make 10 chargable calls on the account and have a credit search performed against your name.
Personally, I think this is a great deal if you are looking for a new line to be connected and don't want to be tied into a contract. This isnt available online - you have to phone their sales team on 0800 073 1120 (don't forget to use 0800buster if you are calling from a mobile). This is also good for students, who dont want to be tied into a contract as they aren't going to be in the property long. The offer is only available until 30th Jan 2010.
You get evening and weekend calls in the £11.25 per month, and this includes 0845/0870 numbers. And as this is a part of BT, you might be able to use override providers.
Hot or Not?
Edit: Included in your £11.25 per month is:
# Evening & Weekend calls to UK & international landines 2
# Evening & Weekend 0870 / 0845 calls included 2
Please note - prices are due to increase from £10.95 to £11.25 from January 2010.