Hi! Potential new owner here!

[Shed]

If you decide to go for the bike, I'd personally avoid any stealership as they'll most likely shaft you for what is a fairly straightforward task.

Whether or not there is any knowledge of a service between 12k & 21k, as a new owner you can always start afresh.

As a rough price guide for the parts:

For around £60-65 total, you can get all the Oil, Oil Filter, Air Filter, Coolant, and renew the Brake (& Clutch) Fluid.

A set of 4 Iridium spark plugs is about £30-35, and full set of brake pads (3x pairs), also around £30-35ish.

You need to get the bike first though, and then decide if you want to tackle a few of the tasks, or if you're not keen, get someone else to do it for you.

You'll find loads of advice on here if you decide to proceed with it. 

[rjt_honda]

Going to see the bike in the morning....... for the first service I would go somewhere to get it done, there are some recommended local bike service garages....  isn’t the exotic stead I normally choose but comes with full luggage and appears in good condition.  Wait and see how it looks in the flesh!