I think a lot of these stories refer to the second generation car (GH) and not the one (GJ) you are looking for. I may be wrong but if you have any horror stories with the GJ car, can you give some links?
All cars develop their own problems but the biggest issue with a used car is the previous owner(s), how they used the car and how they maintained it. The majority of the drivers are not car people and most of them end up with some shortcuts in maintenance either for money reasons or ignorance.
However, it is all about value for money at the end of the day. A brand new car starts from £22.5K, a nearly new car with 6K miles starts from £15.3K, but a 2013 car up 50K miles, starts from £8.2K with 34K miles on the clock. If you get the new car and keep it for 10 years, it will cost you around £2K per year on depreciation. With that money you can buy a "new" car with up to 50K miles every 4 years. I do not expect that a car with up to 50K miles will have been abused to such a degree that it will need expensive repairs. If you buy the £8.2K car and keep it for 10 years, you have an extra £1K cash in your pocket to do repairs every year for the next 10 years. I do not think you will need to worry about the need to pay this £1K every year in repairs.