I have found Noel’s GBBO S08E01 shirt! It is from a shop called Silken Favours, which has many quirky prints created by the owner, who is an artist. It is not currently available. The 100% silk shirt is in the print “Raving Ravens” and cost £265. However—the shop does bespoke custom orders too, which I suspect is what Noel went for, as all the off-the-rack ones have buttons, and his has snaps/poppers (because he is a small child who wants to be a cowboy), and the placket laps on the opposite side to all the shirts in the shop (which only carries womenswear). And his shirt has a very nice custom-tailored fit. There are lots of funky western-style shirts that look right up his alley too. The shop does have notebooks in stock bound with the same print in grey and purple.