already there is a glut of blackberries in our garden which I'm collecting & freezing (before the dogs have them) & an old tree with cooking apples, so it looks like I should make a fruit crumble (or 2). Any favourite recipes for the topping or are there packet ones out there that are edible? I have custard at the ready!

if you don't have time then there are ready made ones in the shop but it depends how sweet you want it as they can be a lot more sugary than if made at home.
i don't make it very often but i like adding some oats for a more crunchy topping and not too sweet. another is to add crushed almonds. i've even had one with coconut added.
enjoy your baking.

A recipe for plain old crumble which I still remember from school (See, my memory can't be that bad then !) is 6oz flour, 3oz butter & 3oz sugar. I have played around with it over the years but still come back to the same recipe, although to alter it very slightly and add an extra ounce or two of butter does make a more luxurious difference to the flavour and texture

I add cinnamon and oats to apple and plum crumbles which is very nice.