I don't like what Tiscali told you.
I ran a web sever from a Tiscali connection for the longest time up until about ~9 months ago and it'll be going back soon. It wasn't in the AUP that we agreed to when we got the connection (they've probs changed it) that you can't run a webserver but what they don't want is open relays. That is to say SMTP servers that allow the relaying of any messages without authentication or restriction because it can heavy bandwidth on their network if someone were to find your server and abuse it.
To be honest though, you could do better than Tiscali. I've been running a web server and a whole host of other servers from my Virgin Media 20Mbit cable for the last ~9 months whilst I've been at uni.
Don't even get me started on Piscali, please. Never been so glad to leave an ISP! The final straw came when I was TOLD that I was on an unsuitable package at home and needed a "business class" package just because I do VPN into here..
Such an entire bunch of knuckledragging peanut munchers..and I can't say as I'd touch any of their subsidiaries now either.
Dont worry when Carphone warehouse buys them we will all be in the big mess :D