I’m under the impression that aerial photography is available for the entire of Wales for free from the Welsh Assembly Government… at least that is what I’m told by colleagues here at the Forestry Commission. Not sure what restrictions there are though.
Similarly, I have here a Forestry Commission shapefile of all of the woodlands in the UK. I will ask tomorrow if there are any restrictions on this data (I’m not really in the know), if not would anyone like to have it to use? I probably won’t have time to do it myself.
The resolution is incredibly high (as good as Google at high-res) and is the same resolution across the whole of Wales. I’m not sure how you would get hold of it really, I think it’s available for institutions such as universities from the Welsh Assembly Government. It would probably be worth contacting them, although I wouldn’t know who to speak to. I couldn’t say for certain whether there are any strings attached, I just thought the community might like to know of its existence.