Adwords Forecasting Question

[jazzydan]

Hi Guys,

First time question. I'm going to be creating some Adwords search campaigns. When I create these campaigns I will be targeting specific post codes in London. I've checked this and all is fine.

However I need to forecast costs for my client before creating the campaigns. Google Keyword Planner only allows me to forecasts volume and CPC costs for London, it doesn't allow me to drill down any further than this.

What would be the best way to try and forecast costs for these postcode specific campaigns? Even if its using a third party tool. Or is it just not possible?

Thanks

Dan