Hi there, mailtophoo

I wasnt able to find the thing you were looking for in one download or location.

But if you dont mind spending a little bit of time putting things together and resizing some of them I believe you can make exactly the diorama you are looking for.

The resources listed below are completely free but will require you to set up a couple of accounts. Its quick, free and theres no catch.

So, firstly, if you havnt already done this, you'll need to set up a free account at these two sites :-

http://www.renderosity.com

and also at

http://www.turbosquid.com

You just need an email address and a couple of minutes.

 I've carefully checked the models and they are all original models offered by their creators, so theres no need to worry about pirated or dodgy stuff.

The Models.

Castles.

These two are either very late Saxon - or early Norman motte and baileys.

http://www.renderosity.com/mod/freestuff/details.php?item_id=64257

http://www.renderosity.com/mod/freestuff/details.php?item_id=60101

I think the first of these two is the better option - if you import it into poser, Daz or carrara you can open/close the doors and gates. The wattle and daub walls are perfect but idealy the roofs should be thatched for the period you wanted - thats just a simple matter of changing the textures.

If you do search in the free stuff section at Renderosity, a word of warning - some of the models are only downloadable from the authors homepage. Users such as "rodluc2001" have some great models for free but also set of my anti-virus and firewall alerts, so they may have become infected at some point. So be cautious and keep your anti-virus on.

Note: I'm not calling anyone out on this or saying that its intentionally infected. I've never had an issue with the Renderosity site, just dome of the homepages the links goto. 

Useful props to enhance the diorama.

http://www.most-digital-creations.com/dry_stone_wall.htm

http://www.most-digital-creations.com/www.most-digital-creations.com_TreeOnAHill.zip

Trees.

http://www.sharecg.com/v/34419/Poser/Free-Tree-Prop-from-Cauldron-Arts

This is a briliant prop - its very low poly so you can resize and replicate or multiply it many times giving the impression of an enourmous forest at no cost.

Have fun,

Maf