Not strictly Penkridge, but someone credited me with a series so it seemed rude to change it!
This layby is popular with truckers so it can be messy, you may not be able to park close at times.
You are looking for a micro container, bring your own pen.
It should be an easy find if you can park close. You don't need to cross any barriers and shouldn't need to rummage around in any rubbish or hedges.
Congratulations to Restmengi for the FTF