You could get either a small or a medium Tab with that plan. If you have any tab owing right now that will have to be paid in full before you can upgrade to a new phone, you can pay your full tab at the time of the upgrade or add it to your next bill.
So I could keep my old plan because when I called they said i would have to pay $5 more for 200 minutes, free calling at 5pm and unlimited texting but I only get 50mb of data. I don't want to pay an extra $5 more because the amount of data in it is useless!
You should be able to use your current $30 plan (150 min, 200mb) to use the Tab M.
You will need to take $35 plan (200min, 50mb) if you are a new customer, but you are already with Koodo with $30 plan.