On that exchange your best ISP by far is
Be. The package to choose depends mainly on what their speed estimator comes up with. You can also get £40 cashback by signing up through TopcashBack or Quidco so long as you do that correctly. More info on cashback if you decide to go that route.
They do not use traffic management and their FUP (covering excessive use degrading the system for others) has never been invoked barring when there was a major cable fault causing significant capacity problems, when we know of one user receiving a polite request to cool it.
As MrSaffron says, no ISP will ignore a court order that says they have to supply details of the user of a specific IP address. On the other hand I'm not aware of any who supply such information without a court order.
Be do not supply email or web space facilities. I recommend against using ISP-supplied ones anyway. See my
ISP-independent web/email page.
My broadband basic info/help site - www.robertos.me.uk
My domains,website and mail hosting - Tsohost.
Internet connection - O2 Standard.