306 2002 ex fuel leaking from filler or breather

You are OVER FILLING the tank, its got to have a breather,so yes it runnimng down the pipe and all over the wheel and your foot.

We had this once when we got our 306 back from an accident repair place. Filled up the tank, paid, came out and found all the petrol in a pool under the car with a significant flow coming out from just under the rear wheel arch.

Garage picked it up again (just caught them at 6pm!) and looked at it the next day. Apparently the filler pipe neck had split - somewhere between the spout and the bottom of the tank. There wasn't any work done on the back (slight front damage) and apparently it wasn't that uncommon on cars of this age (1998) for the pipes to have split/perished or something.

Anyway - all fixed - and thought it sounded like what you have.

Check the rubber elbow where the filler neck joins the tank. A bit of a sod to change though!