Speedstone is the brand name and it covers Granite, Quartz and Solid Surface worktops sold by B&Q, they are not available anywhere else.
It's only supplied/installed by B&Q because it needs to be fitted by trained installers.
The Granite and Quartz also require specialist tools which would be too costly for just 1 job. Solid Surface is cut using a router and then sanded/polished using a random orbital sander, the same process that is used for Corian.
ALL installers must be trained by Sheridan Fabrications (www.sheridan-uk.com), the manufacturer, prior to them being able to install.
B&Q will sell on a supply only basis to trade kitchen fitters, not the general public, if they can prove they've been on the training course, a certificate is awarded once the course has been succesfully completed.
Hope this helps.