Hiya and welcome to TAS
I'd echo the 8-10, possibly 12 on 2 acres - if you're raising them spring to autumn that leaves time for the ground to recover for the next batch. If you wanted sheep too, I'd recommend halving the area and number of pigs - pigs would trash any grass and the sheep would need it

If your ground is very wet you might even need to cut back a bit on numbers too - as it will get churned up all the quicker.
Fence posts are about £2 each (you'd need them every 2 meters) strainer posts are around £10-15 pounds (unless you have larch in your woodland - then they are free cos you just cut down and strip a couple of trunks

) you'll need a strainer say, every 50 meters. Stock fencing costs between £30 and £50 for a 50m roll - all of this assumes you want to fence it yourself

If you're paying someone else to fence it you can pay anything from £3 per meter to £10 plus per meter (post & rail)
Pigs eat 1lb of hard feeding per month of age, per day - so 12, 3 month old weaners would be getting through 36lbs a day (most pig food comes in 20 or 25 Kg bags and costs anything from £7 to £10 per bag) buy the time they are reaching pork weight you'd be looking at double that. They need feeding and checking at least twice daily and constant access to fresh water (but not streams or rivers)
For an 85Kg liveweight pig you'd expect around 45Kg of cuts, joints and sausages. Slaughter and butchery charges vary around the country, but you're probably looking at around £60 to kill and cut each pig.
I would definately advise raising a few batches of weaners to slaughter first, before even thinking about breeding. There's lots of learning to do, to be sure that you're able to handle, inject and know what to look for when spotting problems not to mention that you're committed enough to spend nights with your pigs making sure everything is okay with farrowing or making the twice daily visit in rain, hail or snow

. If you were to go down the breeding route in the future I'd think your maximum breeding stock with only 2 acres would be 2 sows and a boar (or visiting boar - so much easier

) to allow for paddock rotation and to stop overstocking and the land getting pig sick.
HTH
Karen