Mechanic to check out 1.2 or go for 1.4 on my own? (2004 Polos)

First time driver, buying a used Polo this week hopefully.
I will be driving mostly on weekends for both short journeys and also 1-3 hour journeys on the motor way sometimes.

I can check out a 1.2L with a local mechanic. (from a Private seller)
Or I can check out a 1.4L Polo by myself. (from a Trader)
- The mechanic won't travel to the 1.4 at the Trader because it's too far.

Both are year 2004.
Both have a service history.
Both have 1 year MOT.

1.2 has 69,000 miles.
£1690

1.4 has 78,000 miles.
£1400

Note: The trader offers 6-12 months warranty and also delivery of the car too.

My question is, what do I do?
Is it best to go for the 1.4 or go for a slightly smaller engine with reassurance from a mechanic? (if the car is fit to buy that is)

Any help would be greatly appreciated,
Thanks