T-mobile seems by far to have the best fair use policy in the UK. the only provider that won't charge you per Mb after you run the limit.
However it seems that to get full hsdpa speeds, it is necessary to get either a "Mobile Broadband Plus" or "Mobile Broadband Extra" package. It's my understanding that the Web'n'Walk or Internet booster will only get you a speed of about 380Kb/s.
The problem is, that about a week ago, the "Mobile Broadband" options were removed from the sim contracts. here you can see that it advertises "Mobile Broadband Plus: £12.50/month or £10.00/month for duration of plan, 3GB fair use." However that option isn't in the drop-down menu. The only way now to get a Mobile Broadband package is here.
Would it be possible to take the sim out of one of these usb modems, and use it in a phone? And would it be possible to get the phone a number, if that were to work?

Thanks.