In the UK your options in this area will be very limited. It is possible to have a 1Mbps up path on some ISPs and with most you will have to go to a 2Mbps SDSL to improve on that.

At the moment I have a fixed IP on O2, who use ADSL2+ in my exchange, and I get a nice 1Mbps up path with fixed IP for £12.50 a month. I host on that at the moment and while it's quicker than hosting on the 400kbps I had with Zen it's still pretty slow. I do channel bond with the free Sky Broadband I now get to get a combined down path of about 12Mbps which is nice, so maybe having a 2nd line put in with ADSL from another supplier would give you some sort of fail safe as well as freeing up the hosting circuit from heavy use.

Cheers

Cris.