The house you live in can determine the reception quality, so you actually need to be very specific as to where you live! If 3G coverage is bad, then 3G broadband will be bad. See if you can borrow a Meteor or O2 or 3 broadband dongle to test the coverage-or even a phone as both will use a 3G SIM-this is the only true way to test, as coverage can vary wildly over very short distances.
Meteor are a mobile provider, so you don't need a landline.
It's a slight difference, but wifi and wireless broadband are two different things. What you are really asking about is wireless broadband.
FWIW, you will struggle to get broadband for less than the mobile providers charge for their 'midband' service.
Do you have NTL by any chance?