My S3 has 136,000 miles on the clock and runs well and pulls strong. Mechanically it's been well maintained with history to prove it.
IMO, don't worry about the mileage, worry about how it's been looked after. Do MOT history checks to make sure all fails and advisories have been done, and preferably there won't be any.
Check service history if it has some.
A high mileage car doesn't mean it's a bad car. One with half the mileage may have had less care and attention and need more money spending on it.