Please don't do this unless pedestrians are explicitly prohibited by law and there is signage to indicate this (specifically the pedestrians prohibited sign, TSRGD diagram 625.1 https://commons.wikimedia.org/wiki/File:UK_traffic_sign_625.1.svg )..

Access tags in OpenStreetMap represent the legal situation, not an individual's vague feeling about whether a route might not be the most pleasant choice for a stroll.

https://wiki.openstreetmap.org/wiki/Key:access