First up, here's a couple of leaves and close-ups showing what I think are the vacated mines of Stigmella microtheriella. These are thin gallery mines, with linear frass in the early part of the mine.
I also found loads of these tiny blister mines that were all tenanted. I think these are the very early mines of Phyllonorycter coryli, and the blister will get bigger.
Finally, I found this vacated mine that looks good for Phyllonorycter nicellii.
Whilst poking around the trees, I found this sitting out in the open and easily managed to pot it up for a snap.