I let loads of nettles grow this year but cannot see any insects on them
yet, what should I be looking for this time of year and what should I
expect to see now or later

Nettles are food for caterpillars; and aphids, in turn aphids are
food for ladybird larvae. So you should see some caterpillars, aphids,
ladybird larvae, and possibly, adult butterflies and ladybirds.

Other than the insects themselves look out for holey leaves, leaves
wrapped up in web (caterpillar hide-out) and caterpillar pooh.

Janet.

Thank you all for that info. I will go and inspect the nettles but first
I have to go and help clear a tree that has come down across the drive
in the winds last night

kate

Gloucestershire