I took this option too - was already paying for my anytime free calls package. But, moved from O2 who simply do not have a fibre product.
The extra costs are really marginal and worth it for the extra speed. Pretty much a no-brainer.
I had a 59db line, which surpringly managed to give me connection at 5.7megs and downloads around 3.5 to 4 megs most of the time. O2 set me a NM of 3, andI did get the odd disconnect each day, but I was happy to live with that rather than sacrifice speed for stability.
I now get 37.5 megs if I connect to the HH3 via ethernet, and get up to 19megs wireless (and that's to old wireless b/g machines!).
Might try homeplugs (can't really string cat5 around), but the main problem is that my studio is on it's own ring (deliberately, so I don't get clicks and pops from household appliances). I just wonder how well homeplugs will work with round trips to the dist box. I've seen some pretty dire speeds from supposed 200mbs (100 duplex).
But, that said, so far, the service has been great apart from a wee glitch in the week when downloads were slower than uploads (4 down 6.5 up). People suspected there was something being streamed by loads of folk on the net - and therefore affected the whole network.
1999 Freeserve Dial up --> Freeserve Anytime ---> 2005 Wanadoo 512k BB ---> Jul 2009 Orange up 8 Megs(hah!) --> Nov 2009 O2 LLU -> Nov 2011 BT Infinity( getting 37.5 megs now on ethernet)
Yamaha AW16G user