what i did when i bought my 1.6 sport was....
change plugs, oil, filters (fuel, oil, cabin, air)
and then the usuals like checking the...
tread, pads, discs, drums, operation of the air con, condition and level of brake fluid, level of power steering fluid, condition of exhaust, coolant level, spare wheel, exterior lights, wipers
i also put an additive in the oil before i changed it and ran the engine for 15 mins at idle to flush the engine. and i put an additive in the fuel to flush it out nice and clean too.
that includes everything that needs to be done at 40k according to the Seat service plan