Try scalescenes.com for addtional card stock alternatives. They sell in OO or N scale, but HO scale is just a matter of reducing the print size to 87% of an A4 paper size.
There is another very recent thread on this topic in the general forum http://cs.trains.com/trccs/forums/t/171635.aspx.
Alan
Co-owner of the proposed CT River Valley RR (HO scale) http://home.comcast.net/~docinct/CTRiverValleyRR/
Metcalfe and Superquick are two manufacturers of card kits that might be of some use to you.
A quick google or yahoo search should do the trick.
Mike
Modelling the UK in 00, and New England - MEC, B&M, D&H and Guilford - in H0
A British outline layout will most likely be in OO scale, which is much bigger than HO scale. If tha´s the case, you cannot use HO scale buildings at all, as they´d be hopelessly undersized.
Bachmann in UK and Hornby also offers a range of structures and buildings, which may be of interest to you.
Other addresses are available through this link.
Here is a few sites to check out. Britannia Models I have been to and they are very nice. The rest I have not. Sorry they are not clickable but I am using a very old MAC tonight. Good luck.
http://www.britanniamodels.com/
http://www.bsmcl.com/
http://www.eurorailhobbies.com/
http://www.caorm.org/hobbyshops_pacific.html
Brent
"All of the world's problems are the result of the difference between how we think and how the world works."
Hi Alec
Where abouts on this big blue ball in space are you located???? There are a couple of retailers on the west coast of Canada that deal only in British rail. If that would be convenient for you I can hunt down their addresses and such for you.