If you want specific to you, go to any place you can order online. Place a order and go to checkout. Chances are you will be asked you house number and postcode, and from there a "find address" drop down. Simply count how many have the same post code.
What a good idea! I was hoping local councils might have records the general public could view. I suppose the electoral role would do? Do they still have these in local libraries - if any of those are left!!
I should have said up to 24 houses. Where the postcode is in the town it can cover just one or two businesses only.
If your question is about a specific postcode them simply type it into the postcode finder here, making sure you have the find a postcode tab highlighted and not the find an address. It will list all the properties in that patch.
In this road it appears to be one postcode up one side of the street and another very similar one up the other side. I think there are approximately 52 houses altogether so that would make 26 houses to each postcode. (That about does it for me maths wise)
Use to VOA website and look at the Council Tax and Business Rates searches - if you just put in the postcode it brings up all eligible property numbers.