2 years ago, during the unfortunate dispute with your neighbour, who sounds fairly difficult and petty, you said
she will have an embargo put in place to stop me carrying out any work whatsoever on the woodland without her permission
Now, could we make a wild guess as to who might have brought your shed/store to the attention of the planners?
I know hindsight is a wonderful thing, but with this history of tensions with the neighbour and their stated objection to you doing anything, it would have been better if you'd checked out the planners attitude to a structure prior to building it. It doesn't cost anything, you can ring them for an informal chat, state what you'd like to do, and they'll give an informed opinion as to whether it'll be likely to be permitted or if formal permission is needed. I nearly came unstuck doing the same at home putting up a kiln shed with a roof on it, in the end I got permission going through the planning process. The objections raised by a couple of neighbours were ludicrous and hypocritical.
It certainly pays to know the regulations before thinking of carrying out an activity or putting something up, and trying to be reasonable with neighbours, asking them to express any concerns they might have. Jaw-jaw is always better than war-war.