not a good idea, but do-able.....there is plenty of daylight at the moment, so leave early and do lots of 2 hour chunks....should be able to do 30 miles or so in 2 hours, take 30 min to 1hr breaks in between (but keep legs warm with jogging bottoms) eat plenty and drink plenty, wear cycling shorts and shoes you've already worn in, use vasolene, use correct saddle height (your problems might be incorrect saddle positioning ...usually too high)

should do it 14 hours....(10mph) which is what I allow as an avergae when cycle-touring, which includes breaks and lunch and taking photos.

take spare tubes and tools!!!!!

you'll be able to use the vasolene on your quiff when you get there, but send your drape suit and brothel-creepers with someone else....i.e carry as little baggage as poss.