Owning your own home

Land is very expensive currently, even more so if it is land that can be built upon.
Add to this the all time ridiculousness of materials, staff shortages, and it is probably the least sensible time to try this.
https://www.savills.co.uk/landing-pages/rural-land-values/rural-land-values.aspx

You might find it very difficult to get permission to build a dwelling on farm land. They'd want to see evidence that the building was there to support the current use of the land - i.e. if you had a heard of sheep and needed somewhere to sleep during lambing. Otherwise they will just see "residential house" on "farm land"

build a glorified garden shed on it t ouse as a weekend away

A few years ago I spent a small amount of time researching this. It seemed attractive at first blush but looking after land / woodland properly does entail real work and the number of nights you can stay is limited. You also hear horror stories about dealing with trespass etc

https://www.woodlands.co.uk/owning-a-wood/sheds/

Friends of ours have a small parcel of woodland down in Kent/Sussex where they have a hut that they stay in for weekends/school holidays. No electricity or running water but they seem to enjoy it. I don't know how much it cost them, but they are not golf club thread types, that's for sure.

people will pay stupid money to do the very same.
my extended family co-own 3/4 of an acre just outside my home village in kent that was my grandfathers allotment/market garden, it has a shed, half of it it grass, the other half a bit overgrown as it’s a full time job keeping it clear but great for BBQ/parties/camping.
adjoining this is a slither of woodland on a slope that is about 20m wide at the boundary with our field and it narrows to a point where it meets the village, it’s wooded and has no level ground in it. somebody paid £15k for it!? they drive down and sit in the wood for a bit but it’s actually not much good for anything, too small to coppice and do firewood, too dark to enjoy in the summer and no room to have a gathering and no parking.
the family would have chipped in and bought it for £5k as theres a path right up the middle that goes into our field but couldn’t believe the price it went for.

This is all a bit vague, but might give you somewhere to start...

Pretty sure that if a barn has been used for agricultural purposes then you can convert it after a certain period of time. I want to say 10yrs.

Depending on what sort of land it is you can rent it out - say for graising.

My dad inherited one and a half bits of field down in the west country. He always wanted to put a timber barn on it so that it could be converted at some point but never did. Probably more money than it's worth now. Anyway point is he rents it for cattle graising, not exactly passive income, but it covers maintenance costs and it has never really been worth enough to sell. He definitely should have just chucked something up when he got it though.

The main problem with it for visiting is that it's fucking miles from London, so I'd factor accessibility over everything. Still when I was small I enjoyed playing around and helping to cut back the trees the few times a year we'd go.

If you get something that has some established trees you could also look at building a tree house plus making some sort of decking area to make general chilling more comfy. Thinking more

rather than