a few yes.
with adsl as long as you not on LLU which you are not its easy to change with none or very little downtime and usually free, called migration.
isps I reccomend to avoid traffic shaping ie. p2p friendly.
http://www.ukfsn.org/home/internet/a...allowance.html
http://www.aaisp.net.uk
http://www.zen.co.uk/broadband/ZenBroadband.aspx
All have caps but generous cap levels, the modern adsl market has no such thing as a unlimited adsl unshaped connection so its often better to look for something with a decent cap that doesnt shape your traffic, the closest to a unlimited unshaped connection is probably the zen 8000 office product which is expensive.
The ukfsn is the best bang for buck 300gig of allowance for under £20 a month.