Yes, the time for relocation is when the tree is dormant. (Winter time in the UK). You will need to leave as much root ball on as you physically can and water the tree really well for several years after relocation. If the tree is large, you would do better to get the professionals in - they can prepare the tree beforehand to minimise the risk of shock etc, plus they will have the right equipment to actually physically move it. Google *arborist* or *tree movers* in your area.