Can I pitch up in a helicopter in any 'open field' or 'car park'? No, I can't.
Will I need permission then? In this country, almost certainly.
Who should I ask? Well, the land owner seems the best place to start.
Do I need permission? Well, I imagine that a lawyer is about to tell me that no, technically, I don't. Because it isn't written down somewhere.
In practice, do I actually need to get permission? Well, yes. Because lots of people don't like random helicopters (or other vehicles) pitching up on their property without permission.
(Do I want to get into some sort of legal ding dong because somebody resurrected a 7 year old thread without directly answering the question? Hell no!)