I can verify the above works.  I'm on a Tesco 12-month contract deal - £30/month for "unlimited use". 

I had problems configuring this initially - kept saying that it was unable to set up the wireless connection.   (It even did it when I tried to connect my wife's Orange phone).  Here is what I did to fix it on my TomTom Go530

Updated my TomTom with the latest updates (not  maps though - too expensive).

Go through the wireless connection set up using the above settings.

It will probably tell you that it can't complete the wireless connection.

Cancel setting up the wireless connection.

Press the Reset button on the bottom of the TomTom unit - you won't lose any data.  Just takes a while for it to reset.

Turn the unit back on - try to connect.  If it doesn't then go through the phone/wireless connection setup again and it should be okay.

Seems to be a golden rule with these TomTom things - if something goes wrong, press the RESET button!