Lads
looking to buy a second hand disco 4. 5 seater 3ltr TDv6. Mid 2013. 140k miles.

Full service history.

Heres what Im looking for, approximate guess obviously

Whats mpg should I expect to get mostly town driving
Whats the annual running costs if Im doing approx 15k miles a year?
How often should I get it serviced?
What can I do myself to keep service costs down and keep her running as well as she should be
Any surprises like certain parts known to go after X amount of miles?

Thanks