Finding SME/SoHo clients

Hi

This may be OT, but I am planning an advertising campaign and I would
like to target SME/SoHo in the UK.

It's a bit tricky to find the write titles here in the UK. "Mind Your
Own Business" is great, but what else is there? Features Exec, Brad
and ABC haven't been much use.

I would also be interested in any websites these types of people read
for information/news.

Thanks in advance.