OK,you say they've not been pruned for many years,so just how big(height,spread) are they ? The RHS are the top people for fruit advice,and they include resurecting neglected trees in some of their pruning manuals.So try and find one in the library.Meanwhile,here's a few preliminaries:
Whenever you prune cut out dead and diseased branches first.Next,remove any branches that obviously cross, 'open up' the tree.Try to cut ,either with a good saw,or the best pruners you can afford,at an angle away from the tree(helps shed the rain).Carry a rag with bleach/surgical spirit and clean the saw/pruners after each tree.Be aware that some apples are tip fruiters,and therefore require much less pruning.
Presumably you don't know the varieties,if you find an apple day,(yearly here in Tenbury) you'll find someone who can tell your variety just by looking at the fruit.
Lastly, announce to your newly aquired trees that henceforth they will be loved and cherished,by stripping the grass around them in a circle of 3' radius,and mulching heavily with some delicious compost.
Lucky old you,I guess you bought the place because of the trees?........I would have done too. BWs