Spacers did the trick

Well the tyres aren't rubbing anymore but the centre caps still don't quite fit. They are only a few mm out though so I am going to get a mate to route out the centre plastic by enough to get them on. I have measured it and it won't mean going right through the caps so it's all good.
The rear ones might be more involved because it isn't just a depth issue there, the centre of the hub is also too wide. Apparantly this can be simply tapped to shape with a rubber hammer as it is only a soft metal cap... I'll be getting a mechanic to do that though, don't fancy trusting myself to hit my car with a hammer!