The best advice I can give you about North Tea is to get there as early in the day as possible. It is a very popular jumping off spot and competition for campsites for first and last tripping days can be fierce, especially on a long weekend. Since islands seem to be particularly valued by many canoeists, they are among the first to be occupied. So, if you arrive after mid-day, you may want to lower your expectations for an island. On the other hand, that makes it all the more enjoyable and rewarding if you luck out and find a nice site still open.
We booked the West Arm for our last night on two different trips last summer and, coming in late in the day, ended up at the very last campsite on the west end of the lake before we found a decent opening. That campsite has a lot going for it, nice smooth rock landing, good swimming, and a great vista of the lake. On the other hand, all the traffic on the lake goes right by; the campsite itself is heavily overused; and it has a thunderbox without a lid that is near collapsing (the place has obviously been overlooked by Park staff for many years).
Whatever you find, though, I'm sure you will have a great time. While you are there, just think of the all the rest of us poor folks on AA who would rather be in your place.
North Tea from the westernmost campsite closest to the portage to the Amable du Fond.
Mark S.
http://www.ABRweb.ca .. Algonquin Backcountry Recreationalists - Caring for Algonquin's Backcountry