Rather you than me...

Potassium hydroxide nastier than methanol? Maybe if you injected it, but methanol is toxic by inhalation and skin absorption (and ingestion, obviously) as well as being highly flammable. Lethal oral dose for mammals seems to be a few grams per kilo, but you'd see nasty effects with much less - so no, don't try consuming any amount, reasonable or not. I would be very surprised to find significant amounts of methanol in any screenwash on sale in the UK, got a reference?

http://www.pcl.ox.ac.uk/MSDS/ME/methyl_alcohol.html