Ploting UK Postcode sales on a map

Hi Experts 

I have been trying to plot the data in the attached PBIX on a UK map to show sales by county/region as bubles and colour saturation. 

If possible- is it possible drill down into a particular region / area within the uk.

Need help please

https://www.dropbox.com/s/wbj4hyhzi1bkm29/Postcodes.pbix?dl=0