You pleb. You have to look at is as an adventure. Stop at petty stations for a fag/coffee/leg stretch every 45 mins. You wouldn't bat an eyelid at that distance once you've done it a few times. 3 hours ish at motorway speeds. You could leave at 9am, ride all the way down to site, change your mind, stop somewhere for lunch, have a good poo, then ride back and still be home well before tea.