In reply to estivoautumnal:
I've just had a very successful trip to France with my road bike (a Wilier 10 speed with an Alpkit bar bag, a bespoke Alpkit frame bag and a single Apidura saddlebag).
I flew easyJet from Bristol to Nice.
I also packed my bike inside a CTC bag. I removed the pedals, rotated the handlebars, unscrewed the rear derailleur, dropped the saddle and finally, put loads of pipe insulation around the frame. I then put it in the plastic bag (now on its 3rd trip). They didn't bat an eyelid at either airport. They also didn't quibble with me carrying 3 small bags onto the aeroplane (bar bag + saddle bag + small rucksack).
Once the bike was rebuilt in Nice, I put the insulation and bag into the small rucksack (circa 15 litres) and rode into the countryside for an hour or two. I then found a quiet spot and hide the bag under a bush. I picked it up 10 days later at the end of my tour ! This saves the time and cost of storing it in a locker at a railway station.
An alternative would be a cheap hotel for the first night and leave the bag there.