This device is like a smartphone using the sim. Plus it has wifi of course. I do not know you contract but all you need is a access point for wifi use, and a sim with voice and data. If you don't want use data with 3g there are many others tablets.
No. You can just use WiFi with your infinity broadband or with any other WiFi hotspot.. Optionally you can get a micro sim to allow internet connection when no WiFi is available. Giffgaff offer some good deals (giffgaff.com).