"A person after my own heart," I originally thought. I, too, enjoy reading HMRC technical guidance, although I haven't actually taken it to such extremes, instead focusing on genuine deductions few people tell you about (like annual medicals).
Your post was entertaining, but there might be a fly in the ointment! Are you actually carrying on a trade? Your consulting work is trade, but there are rules around businesses having multiple lines of business and what is and what is not considered a trade (see BIM20090 and possibly BIM85740). If your art is not commercially available and making more money than it "costs" in expenses, HMRC would probably determine that this line of business is a hobby with no expenses deductible.
If, however, you are selling this art, it's a fantastic wheeze, and also a quite legitimate one as you would, indeed, be a professional artist. You could, too, perhaps find ways to use said art in your trade such that it would commercially justify its creation, even at a high cost.