I offer this excursion as the model for a new class of IBA events.
Steve and I live a mere 60 miles apart and Dieppe to Biarritz is only 550 miles so we met at Newhaven then rode together, avoiding toll roads, all the way in both directions having shared a hotel room and much sustenance on our day out in Biarritz. This is quite different to the more common IBA approach of riding alone and only meeting up for supper and requires a more collaborative approach to riding (and booze). The lazy ride from Dieppe down took 15.5 hours, the reverse took 12 hours and would have been quite challenging for non-IBA riders. (I find that only IBA riders use the word 'only' when describing a 550+ mile day, others ask how many days we'll need)
We thoroughly enjoyed the riding and the day being hoodlums on the beach but I almost certainly wouldn't have bothered to do it on my own, the company makes the difference.
So if anyone fancies a mini-trip, in this country or Europe, and there isn't already a handy IBA event to tag on to, why not just post a notice in this forum and see if someone will help you with it. Spontaneity is key - no more than 10 days notice, no more than 3-4 days away. If you insist on staying in 5star hotels, you may well be on your own but that might also apply if you want to camp on Scafell Pike in February.