When we were looking to buy we looked at a small house with land and they are as rare has hens teeth.
In the end we bought an unmortgageable bungalow and built something. Now we want to sell that and build something smaller at the side to get what we originally wanted.
I would try and get the planning permission, it doesn't cost that much if you do it yourself, or put the word out locally you would be interested in selling building plots and see who comes along.
The market is a bit dead at the moment, even in the south it has slowed a bit, but estate agents only make money when they sell so do not be pressured in to doing something you are not happy with.
The will be someone who wants your home, probably for the same reason you bought it, its just finding that person, so a specialist estate agent may be a better seller.
It splitting the land makes more sense, sell some, you can only get a mortgage of a house and so many acres, anything over is discounted. Someone may pay over the odds for a two acres pony paddock.
I would agree tidy is really important. The originally viewed our now home when it was owned by the family who had it for over sixty years, everything was old, well worn but tidy. We could not sell our house so someone else bought it and in two years trashed the land and it was strewn with litter. I am still clearing ragwort. So get the fields and hedge tidied, declutter the house even if you store everything you want to keep in a shed.
If you can not mow it all just concentrate of the front 'kerb appeal', the colourful potted plants out the front. I had show house towels in the bathroom and a throw to cover up the cat hairs on the bed. I bought cheap Ikea sofas to dress the living room, the Ektorp is great because you can buy different covers to give a different look.
Think of it as a job but if it makes you £20,000 more its time well spent.