No Fear Bridge is a subscription site that many of my students have enjoyed. It has resources for beginner's although the version of Acol it teaches is slightly different from ours.
You can sign up for one month's free membership.
After than I have negotiated a 25% discount for Surrey School Students for your first year's membership:
First log in.
Then click 'My Account' button.
Select a one year membership from the list and enter the coupon code (email me for the code).
The discount is applied on the checkout page.