This layby is very popular with truckers and has a butty van at various times so it can be messy, and you may not be able to park close at times.
You are looking for a micro container, bring your own pen and you may need tweezers to retrieve the log book.
It should be an easy find if you can park close. You don't need to cross any barriers or rummage around in any rubbish or hedges.
Congratulations to Restmengi for the First To Find (and first maintenance visit!)