Wendy, having just gone through the rigmarole myself of renewal of house/contents, I found that many of the companies now seem to operate on a broadbrush of anything up to �500k on the house and anything up to �50k on the contents. In other words, they aren't to fussed unless you are outside these limits - it cost the same for this aspect. Strange I thought, but true.
Obviously their quotes are very driven by the place you live, your claims record and the security features you can claim.
I suggest the answer to your question on the 'house aspect' is to use �1000 per square metre of house floor area - if you still need it.