BritPoll offers

I've been seeing a lot of Discover offers for the website Britpoll to win different prizes. Each one i see on Swagbucks offers about 10 to 15 swagbucks so i was thinking about trying them, but to get them you have to sign up and put in your information including your postcode, home and mobile phone numbers.

Has anyone ever done the Britpoll offers and received Swagbucks?
And does anyone know if Britpoll is a trustworthy website? Or am i just going to start getting pestered with a lot of annoying phone calls?