Wouldn't you have a map with your deeds? We did for our 24 acres, but it was in Scotland. The fields were all marked out as p & w, which took us a long time to work out being 'toonsers'
, but it showed what was in the curtilage and what was agricultural. We went down teh farming route anyway with sheep and cattle
I have a feeling the the word agriculture is looked on differently in different areas of the country, so your local council (shire) may have something on their website
I'd have thought polytunnels would be agri
Planning permission for commercial polytunnels
Commercial grounds, such as farms, are generally covered by the same planning permission rules as everywhere else, and if your land is over 5 hectares you have rights to erect buildings for agricultural purposes (under a certain size). When it comes to getting planning permission for commercial polytunnels, you’ll need to stick to the regulations in the section above.
Googles and found this from First Tunnels - Generally, you will only need permission for agricultural land if:
You’re applying for grants to fund your project - you might need planning permission
You are changing how you use the land. E.g. you are changing farmland into housing
In these cases, you should check with your local authority before going ahead with construction.
You can find further advice on planning permission for farms on the gov.uk website here.
HTH