https://www.gov.uk/driving-eyesight-rules
From which: "You must be able to read (with glasses or contact lenses, if necessary) a car number plate made after 1 September 2001 from 20 metres."
So Dom, find a car number plate (oh look there's one on your car) and a tape measure (or pace it out).
Save a 30 mile trip, for which "You could be prosecuted if you drive without meeting the standards of vision for driving."
So "Let me see if I'm safe to drive 260 miles by driving 30 as a test with possibly defective vision" is actually illegal.
And if you're not safe, a 30 mile version of Deathrace 2000 as a test does not cut it even if there was no fucking corona virus you utter cunt.
Fuck me, much as I hate little richardjohn: you couldn't make it up.