Jevans

Hello all, Been an Audi Q7 owner for a few months now. Had some small leaks but have a good indie near me who has sorted stuff out. Drove back from Cornwall yesterday, car all fine. Parked at home and saw coolant leaking out. It is up high above the passenger side wheel arch, I'm afraid I cannot be more specific as I am unfamiliar with Audi engine lay outs. Let it get cold, the header tank was over the full marker. Started it up this morning, let it run for 20 min, no further leaks. Went to check the level (after an hour or so) and as I unscrewed the cap quite a lot of coolant came out from somewhere other than the cap. As in, splashing on the floor. Is it likely to be a crack in the header tank or a split hose that is leaking under load? It is booked in on Wednesday so will find out but was keen to know if anyone had experienced anything similar. Many thanks, John