So far, I've found 2 -
http://new.panelsystems.co.uk/newsc/index.pl?c=Craftfoam and 1 ebay seller.
The problem with panelsystems is that they are limited in thicknesses, only doing 10mm, 20, 30, 40, 60, 100 and 150. The DO 25mm, but it's in a green foam and I don't know how good it is - the fact you have to buy a whole box for £30 to £40 + VAT + £10 postage also doesn't help.
The ebay seller I've used in the past is also expensive, but he sells in 2" and 4" thicknesses (and 1/2" I've got off him before on request) and also sells in metric foot increments (ie nearest 100mm). Postage is a bit "ouch" but he's useful if you have specific needs for a project and not a huge amount of cash to invest.
As things stand right now, I plan to use a combination of the two for my current project and associated tileset, but I'd like a cheaper option...
