Rabbit is fair game all year long in England, best and easiest place to get permission is any farmer, they will welcome you with open arms and encourage you to get as many as you can as they are a true pest to the farmer, most will even show you exactly where they are on their land, as mentioned earlier catapults work great, train up on the skill first and practice as you want headshots for an instant death, i train with coloured clothes pegs hanging on thin branches, yellow at 10 paces, blue at 15 and red at 20, when you hit them they spin on the branch and once you are hitting the red ones regularly you will have no bother getting rabbits.
Personal favorite technique is cycling in the dark with a high powered headlamp (catty in hand 10ml bearings in bumbag), as you enter a field full of rabbits spotlight one and it will freeze momentarily and then they try not to run into the light (lamping of sorts), you can hustle them into not running out of range as they won't run into the main area of the beam, practice makes perfect, i also only ever take the best cuts (back meat and the rear legs) so i go in from the back and do not even touch the guts, for me the meat is taken in the field and the carcass is returned to the deep grass for predators, we got as many foxes as we do rabbits here
it is also the easiest way by far to get your meat, pinch the flesh just above the tail and make a cut into the fur, once in peel it back with the knife just under the surface until you can geta grip, peeling back the flesh with the knife and fingers is easy even first time, you reveal the meat, 2 slits either side of the spine and the meat is then easiest to remove by hand, then literally pop the rear legs out of the skin and 2 or 3 cuts and all meat is removed, bag it and move on
Or get the fire going and get the kebabs on