Could do better

Hi I am Jim owner of a ramshackle small 3 bed detached old country property with some land attached. The house seems to have been built in various stages with as many roofs as rooms and all at a different pitches from conventional ridge to flats .We joke it is the house that Jack built. If a had sufficient funds the best option would be a bulldozer and rebuild but that’s not going to be possible financially. We love the position and privacy so are trying to make the best of it.
I have some building/budging experience but no design/architectural qualifications and although I know I should use these professionals my budget is really tight so we try and just use this to buy materials.
The house had some old farm buildings attached and we would like to replace these with an approx 50ftx50ft Flat roof single story open ( no internal supports) building for my good ladies hobbies.
I have joined the forum to glean as much advice about the design structure of building.
My own skills are agricultural enterprises, livestock keeping, small holder field management and keeping out of trouble with the regulations in farming. If I can be of any help on these subjects I would be more than willing to share advice.

North west