I don't know where [in the world or country] you reside, and it might make a difference on available materials, but I would try dried Pampas Grass stalks.
Put down a squiggled layer of a thick, weatherproof glue [I would use Locktite Stick and Seal] on the structural roof. Neatly lay on a layer of straw. Squiggle more glue. Lay down a second layer, then compress the straw as much as possible. Finally, seal the roof with a HEAVY coat of SPAR [boating] varnish. You might want to put a layer of Aluminum Furnace Tape [not duct tape] on the structural roof and paint the aluminum black or brown prior to adding the straw. This would basically waterproof the roof.
A while back, I bought a Shoshony's Treehouse building to use on the layout. The cottage had a fibrous roof [coconut?] on top of wood. By using the SPAR varnish, the building has lasted outside for 9-months/yr for four years.
Notice the roof of the green house. [pic from 2-yrs ago.]
Being whimsical, it was not all that serious. I cut it off of some sort of cheap plastic decoration I found at Michael's and glued it in rows on one of the Michael's bird houses. It lasted three years outside. Some sort of rodent must have been awful hungry this year and ate the entire thatch job.....
If 212 degrees lives in the UK then a shop or garden centre selling bird feeding buildings might suit him. They are often "thactched" with a form of grass anld would suit quite admirably.
By the way Gerret the guy you referred to lives in Australia not the UK but the model village has UK type buildings. Incidentally I live near a place called Cockington which is a period place (in a time warp /DesktopModules/NTForums/themes/mls/emoticons/laugh.gif) and has mainly old cottages and buildings with thatched roofs. In this County there are many such properties but the insurance costs are very high.
At one point I used a Heuga goat hair floor tile. I can't remember whether it was a walk-off mat or not. Here is a UK website for Heuga tiles. www.carpets2floors.co.uk/heuga.asp The tile had a good rubber backing and the fibers seem embedded in the backing.
Here is a photo of it.
Today I was HOBBY LOBBY. They had several plastic artificial "grass" items that could be used for thatch after stripping from the stem. "Welcome" floor or porch mats with a fibrus surface, might be much easier to apply .It would last longer expecially if it had a rubber backing, like the matt shown by Richard Weatherby.
You could make the roof from concrete backer board, then brush on a concrete mix with a brush, simulating the thatch texture. Then paint. If you have access to clay/kiln you could cut slabs of clay for the roof, texture it with a stiff brush(or wire brush) let it dry(between some sheetrock boards to keep it straight), then fire it to Cone 5(high temp) in a kiln. Your local art teacher may help you out. Jerry
I was given a book written by John Constable called "Landscapes in Miniature". There is a section that outlines building a thatched roof. He uses a soft natural fibre broom with 4" long bristles. Basically, you cut the fibres with an exacto knife and then lay them out and true the edges as necessary or as desired. Of course the book goes into great detail about how to lay them out apply the adhesive and so on. The publisher is: Luttworth Press Guilford and Sheldon Press London. I have to say the final product is amazing. Good luck with this project.