I fully understand your concerns mate, I've been thinking the same for a while now. I think that we worry too much about our cars and if they will break and how much they will cost to fix...maybe it's just something we do as we get older and over analyze things more!!!
Looking back to when I was about 23-24 my dad had a Vauxhall Carlton Automatic CDXi, it was a lovely car and when he came to px it they took the P on the price, so much so I said if you're letting them have it for that price I'll have it. I ran that car for 4 years and it didn't miss a beat, the gearbox was serviced for about £50 and was still going strong when I sold it. Not once did i worry about it going wrong!
I'm due to collect an A5 s-tronic anytime now (my 1st s-tronic) and was thinking if I bought it would it go wrong....but then you see how many older out of warranty cars have it that are on the road and still going strong!