Not got half an acre let alone an acre like Smokin has but his post is exactly how I clear ground. Cleared large areas on a friend's 6 acre plot. It had brambles, ivy, nettles, bindweed, Coltsfoot , plus varieties of planted mint, comfrey etc etc. (I actually removed large Leylandii,,sycamores and the like by hand ...where I got the strength from I don't know ....but the swearing, cursing and threats helped )
There is nothing like physically digging over land ...if you can. Weedkillers are far more effective when the foliage is hacked back first.
Yes, a regular bonfire on site and persistence. I found a heavy duty lawn mower with blades set high very effective too. Hacking back tall woody stuff first, raking back, adding to bon fire pile and usIng the mower. Very, very satisfying to see the clearing ground
So far an orchard, a veg plot, an ornamental garden, a greenhouse, pond, arches, seats, patio, shrubbery, etc have replaced the wilderness. To come is the "quarry", an area that is huge, overgrown but totally sheltered from all winds. Frost possibly a prob but I don't think so as the site overlooks St. Michael's Mount and the bay. Exciting possibilities.