Small early medieval churches that are still extant are rare, and rarer still are those that have been unaltered in subsequent centuries. Nonetheless, a general purpose church for western Europe is not hard to put together. The basic elements are a rough stone walls, and a small tower of stone or timber frame.
For this church, the stones are cast from Hirst Arts, mostly molds #70 and 71. The tower is made of foam core and craft wood, and the removeable shingled roof is from premade plastic sheets used by model railroaders.
The good Brother points out a roof in need of repair to the local noblewoman, hint, hint...
For the interior, I am looking at purchasing an altar/pulpit and benches from some fantasy makers. Temporarily, I might go with some papercraft furniture.
I am make no claims of full authenticity, but it fits in with the period. Some research I did (post construction) showed that most of the pre-Norman invasion Anglo-Saxon period churches used double windows on the belfry tower and more rounded windows. A link to the article (with illustrations) is below: