Hello and welcome,

Congratulations you have realized there is more to RC than boring holes in the sky. Be careful as pattern can be very addicting.
The first thing I would check is to see if your elevator is deflecting straight. It can be flexing in pushes and causing the roll. A lot of smaller planes use a one piece elevator that can flex on the ends. If this is the case it can take some creativity to reinforce it or you may do better building a new elevator.
http://nsrca.us/faq/94-pattern.html
Take a look at this link. It is the FAQ page for the National Society for Radio Control Aerobatics. There is some good info there and some links to other trimming info.
Also, check the contest calender July 12 there is a contest in Hudson, NH that would be a great opportunity to try your hand and meet some other pilots in the area. You can learn more in one contest than weeks of flying on your own.
Good luck and keep trying.