Would confirm that Lidl UK (Hampshire) have the A4 Photo Paper in stock plus a pretty good selection of Ink cartridges. These included 520/521 series HP364 and assorted Brother/Epson @ £2.99 ea. or £5.00 for 2.
I purchased a pack of paper and a set of carts for my Canon MP620 to try.
Here in europe we have Netbit and Sihl and in the USA there is Costco. I think Sihl should make larger sheets: A3 and A2 and sell them in the Aldi or Lidl. If we could get 25 sheets of A2 for about €12 (4 sheets of A4 makes 1 sheet A2, so 100 sheets A4 equals 25 sheets of A2)