Hard to put a price on it. I think it is a good time to sell, although if anyone has / had plans for touring this summer, they probably have their bike already. Mind you the Nomad you are selling isn't for a quick summer trip, it's more capable than that.
This link shows Nomads that were recently sold on eBay.Meaning of colours / strikethrough of final prices on eBay:
This link shows some expired ads from Gumtree. Here's the Nomad geometry table, your 590L highlighted:
You could also state how used the rims, chain, sprocket and chainring, brake pads, cables etc. are. Any dings to the frame, rust, are the wheels true. Service history including Rohloff, oil changes, does the bike come with paperwork. These all change the price. The more info you give the better. If you are not in a rush, you can always advertise it for an optimistic ( higher ) price, then (later) add "or nearest offer".
You could try selling it locally, I am sure Nomads are known in mainland Europe too. Otherwise if there's serious interest in the UK, you could post it to a friend in the UK and ask them to do the sale for you, face to face. I have bought a bike like this before. Safer for both seller and buyer. Just make sure you do it before Bregzit, otherwise you might never hear from your friend again
This all is just my opinion.Hope it helps at all. Apologies if some info is too obvious.
David