I rode an antique Diversion last time I was in EU. Am sure you can rekindle the stories of me and Martin in the Alps.
If Otto is a little long in the tooth, so am I. You know I have tools. You'd have to deliver to mainland EU though, as I don't drive on the wrong side of the road Probably never will... much less on your A40
Otto is very long in the tooth (200k miles). I would ride him anywhere but then I've been riding/maintaining/rebuilding him for 20 years now.
Delivery to the EU would be awkward though.
The A40 is an excellent road, so long as you avoid the crappy London bit inside the M25.
From west of Oxford to Fishguard it's a hoot to ride so long as you avoid Cheltenham and most of Gloucester via the A436/A417.
The bit from Abergavenny to Llandovery is also pretty scenic. I remember riding along there with Jesal. We pulled over to watch 2 Tornado fighter jets playing low level "chase me" in the valleys.