Strange that they only installed broadband.
When I lived in a tower-block (14th floor) cable had TV, broadband and phone installed. (I actually enjoyed living in the block and being so high up, lovely large rooms - large kitchen, large bathroom, large living room, large bedrooms, bigger than the houses we've had).
There's draytel mentions above and Sipgate and
www.voiptalk.org/reallyvoip and
www.orbtalk.co.uk
There's VoIPDiscount, VoIPStunt and some other Betamax services. These might not issue you local number, but you can get a number for free and point it at the service so you can receive calls on the number and you can set the service up to send out the verified number as the CLID.
I use a PAP2 ATA with VoIPStunt.
I was VoIP only for over 2 years, but Virgin offered me the phone line installed free and no monthly charge for it. OK in reality I'm paying for it in a way, just not the full price as I'm getting a discount on my package which discounts my whole package which effective discounts, the phone 100%, the TV and broadband.
I do have a local number issued by VoIPStunt, but since having a land line I have it send out that number instead.
There other providers I forget at the moment.