Supply house spares for supermarket own-brand tat is very limited - that's one of the reasons it's cheap.
https://www.espares.co.uk/search/mo2219853/lawnmowers/powerbase/m1g-zp3-300c1
Your best bet is to determine the part number off the switch itself and see if you can get something like it off eBay or Amazon etc.
Sdjdj
June 2022
Automatic Answer
We may have found other answers which could help you.
howtomendit.com for free repair help, information and advice.
Try fixfault.com to fix lawn mowers.