Thanks everyone for all of the advice.
I am meeting a planning consultant at the property in a few days and will keep you posted.
One of the things I forgot to mention is that the house is an unusual design.
It seems to have 4 rooms, with two entrances.
Unusually the house seems to have been built into the ground, so you step down about 4 steps to enter, with the window openings being just about a foot above the outside ground.
One side of the building has a slate roof, held up by what seems to be pretty old wooden posts.That side has two rooms.
The other side has a further two rooms, but no roof, although there appears to be more modern window lentils/sills.
We have seen the old ordanace maps and it clearly looks to have been marked out with trees, the more recent maps that are photos, from around 1995 have what appears to be the house although the detail is bad, the position is spot on.
With regards to what we would hope to build, well that really depends on the planners, but the idea would be to strip away some of the trees and have some really pretty plants, with at least some space given over to grass.
The house would probably be very similar to an old cottage,in fact to start with we may fix up what is there.
But if we were allowed, something like this may be nice....(the bude)