Limiting Amount Of Records In A Table?

Hey! I'm doing Computing AS level and the coursework is to create a system for "Terry's Turkey". This is basically my first introduction to Access, and our teacher is little to no use!

After alot of work working out things in access and reading alot of books, other than creating the switchboard, theres only a few things left to do!

The first is to limit the amount of "turkeys" that can be ordered. I have 2 tables that this envolves... Order and Customers, they have a one to many relationship (each customer may place one or more orders, each order must be placed by one and only one customer). They are linked by Customer ID. I need to set two limits, I guess by a validation rule of some kind. The first is that each Customer can place no more than 5 orders. The second is that their can be no more than 40 orders in total. A slight complication to this is that a customer can "cancel" an order, in this case its marked as cancelled (theres a yes/no field called Active to determine this), and ideally, these wouldnt be included in the counts.

So far I have the following as a query, though I have no idea how to put this into a validation rule
SELECT Count(Orders.OrderID) AS Var1
FROM Orders;

I guessed that to expand this to not including inactive orders something like
SELECT Count(Orders.OrderID) AS Var1
FROM Orders
WHERE active="yes";

Any help at all would be most appreciated! I have spent many hours pondering over this is and looking at as many access sources that I can! I think this is my last resort :(