I'm not 100% sure but that doesn't sound as though it's allowed.
If you have a CPL and an AOC then you can advertise and charge "passengers" for the privilege of flying with you as much as you want! However a contribution to your costs is a very grey area of the law. As long as no benefit is received from the flight by a pax, ie. no one-way flights then a contribution is allowed on a PPL. Taking a non-flying passenger through advertising and a set cost, say a quarter or a half would seem to me to be a commercial flight and would therefore come under those rules.
