There's also the option of Virgin Cable in your area but this can be rather iffy in a block of flats.

Cable doesn't require a phone line but with the offers VM do it's almost exactly the same price over the contract anyway.

Yeah, I don't seem to have Virgin wiring, and was a bit put off by the reports of serious over-subscription.

I ended up going with Vivaciti, who also turn out to have cheap no-contract line rental. Thanks all for helping me make sense of this!