I can recommend the above post, Yorkshire Deer Stalking or YDS, he has started some good trips and at very reasonable prices.
As with all truly wild animals nothing can be guarranteed but with his 'all inclusive' trips you have nothing to worry about when stood on your peg, shoot whatever presents itself and don't worry about what money you have in your wallet.
If you are lucky you may be the 'Pig Magnet' and get all the shooting or you may be the guy stood next to your mate who gets all the shooting !
Whatever happens you are bound to get excited when you hear the sound of the dogs in the distance and as they get closer the adrenalin rises and then the 'Black Shadows' suddenly appear as if from nowhere and all hell breaks loose.
Or you may be the lucky one that gets a pig sneaking towards you, not knowing you are there, and you freeze until it is close enough or clear enough to get a shot.
Whatever happens a Driven Boar hunt is an experience worth every penny.