Use of natural stone or rock as one wall of an extension?

My house is built quite close to a solid rock face / wall - that is about 10/12ft high. It's on a hillside in North Wales. I would like to extend the rear of the property - the kitchen - by about 6 ft but this would take the rear wall right up to previously mentioned rock face! (I said the house was close!!) my question is, would it be feasible to use the rock face as the actual structural wall rather than butting up a brick wall against it - which seems a bit of a shame, as this rock is VERY solid, not crumbly at all, and is a kind of granite/slate type consistency? If the rock could be used (I'm sure the whole house is built on this stuff!) then the required single story extension to the kitchen would be quite a simple job of building the two side walls and covering the structure with, say, a glass conservatory type roof - to allow for light in the new larger kitchen. I realise what I am describing really needs to be seen, but the question is more about if the rock is as solid as I'm saying it is, then is such an idea plausible?