Do yourself a favour and get something like a Volvo!
Yeah, servicing on time is essential with the petrols with regards to cambelt etc. Check for no beeps etc, check the oil, if its on the low side, walk away, a sign of bad things to come in most cases, same with the water level.
Noisy tapping on start up then dissapearing will be the variator in the petrols, not a biggy but does need the removal of the cambelt to change it, not a major prob but will effect performance and economy in the long run, so try and sway that in if there is no sign of it being changed, same with the water pump, that is only an extra 50 or so quid, but again still requires the camblet off, so check all these have been done.
Selespeeds can be troublesome and expensive if the go seriously wrong, but thats usually not the case and just a simple recalibration solves most issues, check for beeing overly jurky pulling away, changing gear and check the pump primes when you open the door if your going down that route.
The guide gives better advice than me on these
Anything else is the same as usual but the guide on here is a very good read, and full of usefull info