Since you are looking for "sensible offers," it helps to know that for a 2018 model in this condition—especially with the May 2024 service, Motor Mover, and Al-Ko ATC (anti-snake)—these typically list between £13,500 and £15,500 on the private market.
To help you get the best price, a few extra details can make a big difference to buyers:
Solar Panel: factory-fitted solar panel on the roof?
Weight (MTPLM): maximum weight? (Usually around 1200kg for this model, which is a huge selling point for smaller tow cars).
Included Extras: including the leisure battery, gas bottle, and power lead