Help with apple tree

[cashmerecardigans]

We moved a couple of years ago and have a garden with a well established apple tree. Last year we had a fantastic crop but this year the tree has struggled. We noticed some brown clumps of leaves, which we tried to remove but I noticed yesterday that the fruit is rotting in places whilst still on the tree.
Obviously this years crop looks like it will be badly affected but I wondered what we should do maybe over the autumn to help it recover.
Can anyone advice? We're not natural gardeners at all, still learning, so I wonder if we need to get someone professional in to look at it.
I'll try and post a couple of photos

The weather this year has caused jt

I don't think the weather's helped. I suggest you remove all rotting fruit and foliage, you may have to repeat. It looks a bit crowed in the crown of the tree so suggest you open it up by pruning in the winter once all the leaves have dropped.

crowded!

If a tree carries more fruit in one year than it can manage, it’ll have a small crop the next year. This gives it the energy to have a big crop the next year, and bingo! you’ve set up biennial bearing

Thanks so much, it's good to hear it may not be anything too awful then. I'll make sure we remove the rotten fruit this weekend