Hi
Depending on what type of person you are and what you do during the course of the day, you can get a bumbag if you go out without handbag or get a cheap pencil case to go in your handbag to hold the bg meter, teststrips, pricker, insulin pen or disposable syringe etc. .
I tend to not take out a spare cannula or cartridge unless Im going away for a couple of days. If something goes wrong with the pump (failed delivery) or the cannula starts to hurt, I just turn the pump off and use my insulin pen to deliver the bolus and basal that the pump cant and sort the pump out when I get home which is usually within 4-5hrs.
Best thing to do is wait until you get the pump and then decide what you need to buy. Most things needed for pumps can be sourced fairly cheaply from the shops.