I've had a play with my images after photoshopping.  I've inserted image into word, printed a couple test pages - bit of a tickle in size and seemed pretty good.  I test a test print onto the clear label stuff.  I cut it out and stuck it over the top of mylar in place - just as a test.  Now, no white 'printed' out - as the backing sheet was white it looked 100% but as soon as I removed it, it looked worse.  I may need some further advise in relation to this 

I have also found that images created in Photoshop can be opened with Paint and the size is automatically the same as the Photoshop file.
So, if you get your Photoshop file size correct first then it will translate into Paint at the same size without the need for any re-sizing / guesswork. Remember, you will have to export your file as a jpeg to save it so it will show on a PC that doesn’t have Photoshop installed.
So – firstly save it as a PSD file on YOUR PC ( for working on it in the future ) then export it as a jpeg so it will be viewable/printable from ANY other PC

For sizing, are you aware that you can have Photoshop show you ‘rulers’ on the side and across the top of your workspace?
That way you can pretty much get the size right from the get-go as you can drag ‘guide lines’ onto your workspace to ensure your image is correct to the closest mm.
From memory, you click options and tick ‘rulers’ – if that doesn’t work, PM me and I will check how to do it again and let you know.

You MAY have issues getting colours correct as colours on a PC screen can vary GREATLY from what comes out of a printer.
Once I have my sizes right, I often have to print about 20-30 colour variations to get the colours correct or even close.
So I create the file at home in Photoshop, also save it as a jpeg 20 or 30 times on my memory stick bring the colour variations to work on a stick and print it at work by opening the files in Paint then once I have my colour correct I change my original PSD file to THAT colour at home and print my final copy at home.

Hope this helps, PM me if you want help.

I need to get some calipers (measuring type) from bunnings to get accurate readings, and I will try this method next.!