Data mining, email address searches

Hi,

I need as many contact email addresses for builders in the UK that specialise in building loft conversions. The companies will be found by google search using:
Loft conversions *cities in book 1* or Loft conversion companies *cities in book 1*

I will need 150-200 contacts for London and a total of 300 from the rest of the cities (with number of contacts from each city relative to the population)

Email addresses are to be broken down by city.

So approx 500 contact emails in total.