If you find the car pulls to the side when you accelerate and brake then, there is a good chance your front wishbone bushes have worn out. This will be particularly notiable when feathering the throttle mid corner as the car can feel very unstable.
The parts you need from Peugeot to replace these are:
3523 31 Front Bush - 11.08 GBP
3523 23 Rear Bush - 13.86 GBP
There is a kit with both these in as well as all the bolts for about the same price as the two bushes
3599 07 Kit Flex Joint - 26.89 GBP
This contained enough bushes for both sides so was considerably better value.
Polyurethane bushes are available and there have been mixed experiences of their effectiveness on 205's
Replacement wishbones from motor factors come with bushes readily fitted, but many often remove these from new and fit genuine Peugeot ones / poly bushes for better longevity.
Other causes could be an ovaled ball joint hole in the hub, causing movement of the hub. This is caused by wear of the pinch bolt in the hub or incorrect torque settings of this bolt. Unfortunately this may render the hub useless (unless sleeved by an engineering firm).
Another cause may be the ball joint itself. This can only be replaced with the wishbone, unless competition rose jointed wishbones are used.
If there are still issues then it would be a process of elimination from Track rod ends to suspension top mounts, to tracking settings, sub frame bolts, tyre pressures etc...