Hey Tom,
apart from your personal docs, sunglasses, a calculator and a couple of pens, you will need to have a bag big enough to carry the paperwork for the day. Weather, notams, plogs, etc.
All this can be carried in a Marks and Spencer plastic bag (or any other reputable store) although your street cred may well suffer.
Depending who you fly for, the most important items you will be taking in your bag will be your face feed for the day plus a magazine/newspaper. This will fill any spare space!
I would suggest getting one from Argos rather than splashing out too much of your hard earned. 737 size too!
Best of luck!