Standard clay cartridges are fine. Plastic & fibre are ok at the A1 too. The birds are all fairly close - I would not think you need much choke if any either.
If you have not done Helice before - it is a bit different to clays. The 'bird' is made of two parts - the 'wings' and the witness cap and you must hit it with sufficient force to break the two parts so the witness comes off the wings. It doesn't take much - just a direct hit The witness must fall within the fence/ring of the field. One bird, but you can use both shots in your gun. Need to be quick off the mark.
Thanks for the info. Randomly I looked at your other videos and saw the gyros one and other than making me very hungry it reminded me of good times in Zante visiting my brother.