No, don't stay in beginners if you're running a good pace, you'll go crazy being constantly stuck and unable to pass! I only started going to the track late last season, and for the 8 or 9 trackdays I've done, I was probably passed 4-5 times total. IMO, if you read a lot, educate yourself and make progress every time you're out, you'll only get to practice being passed after you get to the expert group eventually. Usually there are so many very slow slow slow people in both beginners and intermediate, that unless you get a lap-timer and manage to find a gap to squeeze laps at your 100% without being slowed down, you'll never know how you're actually doing.