What would be your top plant recommendations for supporting food chains in smallish Yorkshire gardens with room for at least one tree?
Plant native species as they will have many more insect associates and so support other creatures that eat insects, especially birds. It’s hard to beat apples and pears for a small garden: fabulous flowers, of course fruit (both for you and the blackbirds on the windfalls), and plenty of insects that eat them (even the cultivated forms).
Other small native trees would be field maple and sallow; the latter has wonderful catkins in early spring that provide nectar for bees, moths and (yes) birds. For non-woody plants, again use natives where possible; often the commoner species have the most associated insects. If planting garden forms, be cautious about ones that flower for very long periods, because that probably means they are sterile and not producing pollen, nectar or seeds.