Anthouse sells blocks for relatively cheap, not sure on size. Not UK though.
Link : http://www.anthouse.es/en/materiales/45-product-45.html
I checked 5 euro each and shipping is really good considering weight.
Bhu Yonten wrote:Antstore sells some.I also sell ready made nests( 10 x 10 width and 5 cm thickness for 6 pounds + shipping) non carved blocks with glass ( 10 x 10 width and 5 cm thickness for 3 pounds + shipping)
I started ant keeping when I was younger but never[…]