Data collection online

Creating a clean list of postcodes of venues from a specific business' website - e.g. a list of postcodes of all of the Starbucks coffee shops in the UK. The raw data of the venue addresses will be openly available from the websites and/or Google Maps (I prefer to use the actual sites' venue finder/store locator pages than Google however as they are usually more accurate and up to date).

I need someone to copy/paste only the postcodes into a single column text file or excel spreadsheet.

E.g.
W1F 7HH
WC1B 3BA
W1J 8ET
W1S 2BX
SW1H 0AZ

It can be done manually or if someone has the skill to do it much more quickly via a script. I don't mind how it is collected (provided it's legal) but the list must be complete (or as near complete as is reasonable to ask) as error free. The fixed price I am quoting is per 1,000 postcodes.