Minimodels - 1/100th paper models from this Czech site. Highly recommended!

Office Direct - a good source of card.

Papermodelers - join the forum to get loads of ideas and help!

Scale Model Scenery - for models from 1-72nd to 1-24th.

Model Railway Scenery - for models in N, OO, HO and O scales

Model Railway Forum - what it says, really.

Model Railway Shop and Railway Modellers-  "small ads" site where you can buy and sell railway-related items.

Scenery Expert - helpful hints about all aspects of scenery-making.

Hobby and Model Centre Bolton - not a huge shop but extremely well-stocked.