Apple Tree Infestation help please?

The first picture looks like rosy leaf-curling apple aphid.
It is one of the more damaging aphids that attacks apples often in preference to anything else.
It makes the new growth unsightly (the damaged leaves often drop as the plant due to their toxic saliva injections into the leaf and as the plant tries to defend itself).
Rosy apple aphid can de-vigorate a young tree, but the larva of natural predators such as ladybirds, hoverflies, lacewings etc will eventually come along and eat them as long as the tree is not sprayed with insecticide, which will affect slower-multiplying predators more than the fast-multiplying pests).
Mature trees should be able to withstand infestation.

The second and subsequent pictures look like "winter moth", which is another common pest of apple.
The caterpillars don't usually cause much damage to fruits, but they can make the leaves tatty.
Birds and wasps will take a few. The remainder are unlikely to cause much damage to an established tree, but can be de-vigorating on young trees.

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Either pest can be killed with insecticide, but other beneficial insects may also be killed.
I often find bees on my apple trees, feeding on the sweet sticky aphid excrement, so spraying the aphids also risks killing bees.
The caterpillars would be more easily picked-off and squashed if they are troublesome.

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Judging from the pictures that show plenty of healthy leaves in the background, I don't think that you need to take any drastic action. My apple trees often look a lot worse than yours

Many thanks for that FB :0)