Although I am going to recommend Virgin Media "cable", there is only one down-side that comes to mind and that is their "Traffic Management System" (a search here on the forum will produce a link explaining the rules exactly)
This (basically) operates on the basis of you either DL 800 MB or UL 325 MB, but either way it is a total of a combined UL and DL of 800 MB whichever figure you reach first.
The starting point is from between 4PM and 9PM.
If you fall foul of these rules then you are "traffic Manged" on a much reduced rate for the next 4 hours from the time you hit a total of 800 MB UL & DL.
For a 4Mb connection the cut is down to a 1Mb connection.
But with careful planning, observation and depending if your client uses a scheduler then it is possible to live with the restriction (well just about)
Other than that, VM have no other restrictions or caps.
But they are also not the cheapest.