@bushcraftlearner83729: I mentioned Planning because in some authorities, putting hard core down for vehicle access needs permission.
What local authorities don't typically like is anything which
they feel might potentially lead to breach of a policy such as "no new dwellings outside designated areas or as infill." Things like hardcore going down for parking on agricultural land, from a person living in a van, is likely to be see as the start of a slippery slope towards trying to get permission for a residential development which otherwise wouldn't be permitted.
I don't know what your long-term intentions are- only you know that- but you come across to me as someone who lives in a van, has bought some land and intends to park on it and live there, and try to live self-sufficiently. Whilst this may be a laudable aim, there is nevertheless a bunch of bureaucracy governing such things, and if you want to navigate that successfully, a clear and realistic plan is required.
Willow: the bare-root (bare root- not cut rod) Salix verminalis
will establish in a boggy area in grassland without weed suppression, but they are slower to get away and then grow more slowly. The retailers recommend cutting the competing stuff down and then putting weed suppression down for the first could of years. (I've been experimenting with various planting on a damp Welsh hillside the past couple of years so I am speaking from recent experience. I have had some successes and a bunch of failures- which informed my final plans).
If you want to cut an acre or two of rough Welsh hillside grassland then (again from experience), I strongly recommend getting a big petrol-driven brushcutter-strimmer- a decent make like a Honda, biggest engine they do, you'll also need an arb mask, ear defenders and safety glasses under the arb mask- and get a set of ballistic boots if you want to use the blade rather than the line. It's still hard work but is doable for one person. (Or you could use a scythe- if you have or cna learn the skillset- but you would need a decent ditch blade, Scythes Cymru have a good range and do courses too).
GC