planning Application

You will have to use a GIS tool. I would recommend QGIS. The Composer tool allows an A4 sheet to be laid out with the typical contents expected for this sort of thing & you have good control over scale.

If incorporating an exported image into another document set the dpi to 254 and then there will be a straightforward relationship between metres on the ground to pixels in the image.

However, the available raster tiles will probably not be suitable (for instance text will be difficult to read), so you may need to use OSM vector data and style it yourself.

OSM has been used for at least one planning application in England & Wales. Whether OSM data are suitable will depend on the nature of your application.

I personally have not created maps at this scale with OSM data, but I have made maps at 1:5000. I started with OSGB Open Data Local (which has style sheets available for QGIS), but relatively quickly found that OSM data were preferable for many features (largely because they are better attributed).