UK Postcode Distance Spreadsheet Automation

I need a ready-to-use spreadsheet that calculates the driving distance, in miles, between two UK postcodes. I’ll enter the “from” codes in column A and the “to” codes in column B; column C should then fill itself with the correct mileage as soon as I add or change any postcode.

Feel free to build it in Excel, Google Sheets, or another widely available platform, but it must refresh the figures automatically without me having to press extra buttons. If your solution relies on an API key (for example, Google Maps Distance Matrix or a similar service) please include clear, step-by-step notes on how I add my own key, so the distances continue to populate after delivery.

Deliverable
• A working spreadsheet template with columns A-C configured as described
• Built-in, automatic driving-distance lookup in miles
• Brief setup guide covering any macros, scripts, or API connections needed

Once I can open the file, type two postcodes, and immediately see a correct mileage based on real-world driving routes, the job is done.

Deadline: Thursday