Thanks for messages of encouragement. I'll write a bit more about the ride when i've gathered my thoughts (which are going to take some gathering!) but some things that spring to mind are:
1. The phrase that came into my head to describe this was ' the adventure of a lifetime'. That's my best five-word summary
2. The last bit was the hardest, the 190km from Alexandroupoli. Did it through night. Started off slowly, then thought I'll blast it, but got sleepy. Slept a bit, woke up and couldn't quite accept the situation. Thought I was in a dream and had editorial control over what happened. Gradually realised I wasn't and the only way out was to ride further, not to just wake up. So blasted the last 60km, in the morning sunshine, helped by great company from my shadow, who emerged when the sun got up (ok, you look like you have a great position on that bike but where were you all night when I really needed you for company?)
3. Next hardest was the Croatian coast with hurricane-force cross winds. Got blown off twice, walked some bits, couldn't walk at times and was very scary trying to handle bike on busy road.
4. The big passes were ok. Mostly fitted them in at night so didn't see much, but just spun up them with very low gears (one lie in there!)
5. Main lessons I learned were about how little you need - it was less than I thought. Things like needing to clean your teeth and change your shorts get stripped away to reveal a more simple purpose beneath. It feels empowering.
6. Dogs. More rubbish written about dogs than just about anything. Essentially there are packs of strays. If one wants to bite you he will - you have no control. You can't outride them. Generally they don't so best jsut to ignore them. But I got followed by a lovely dog in Croatia for over an hour. I'd like to find it and adopt it if I could work out how to go about it.