I would suggest you move it as the leaves start falling in a few weeks, around mid October – this will give new roots a chance to grow before winter sets in.
First give it a good framework pruning to make it easier to handle, cut off low branches in the way of digging and lifting it. Dig a trench 1 spade deep about 40-50cm RADIUS around the trunk, severing the main roots, and ease it out with the help of a couple of strong men, shovels, and levers of timber stake or crowbar or something. You don’t need to ensure all the soil stays on, but a bit would help.
Prepare a planting hole 1 foot deep with a suitable diameter and drive in a really strong stake off-centre in the base of the hole. Position the tree against the stake so the trunk is snug and tight to the stake, but don’t tie yet. Back-fill with loose dry soil, and when the hole is well-filled, vibrate the tree up and down to settle soil into gaps. Use a hose, or plenty of buckets of water, to ‘slop’ the soil right through the whole rootball, saturating the soil to ensure all gaps are filled with soil, all the while making sure the tree is still snug against the stake. Add more loose soil if necessary, but leave a slight hollow rather than a mound at the planting hole, so that in dry conditions next spring and summer, its easy to give it a few buckets of water that will soak in where its needed.
Then finally tie the tree really really well to the stake to ensure there is absolutely no give. After reducing the framework branches of the tree to maybe 2 thirds the height and width it used to be, prune off most of the small twiggy branches and spurs, leaving a framework you are happy with.
All going well, you will have good growth next year, and maybe even some apples!