Thanks for sharing. I just bought a new set of 18" rims last week for my 7.5 and also purchased 4 new PS5 tyres from ATS Euromaster this week to be fitted next Monday.
Got the same deal as you. However, I wasn't aware that we could claim £50 back from the Michellin website so that is really handy and will do that as soon as the tyres have been fitted.
I put a claim in earlier this week for the Tesco gift card, they came back rejecting it as I need a receipt to prove they have been fitted so will have to wait until after next Monday.
One thing to note too, if you are purchasing 4 new tyres from ATS, you can get half price front and rear tracking/alignment, usually £75 but reduced to £37.50. Definitely worth adding that in.