42 years old here too. I'm playing since december 2015 somewhere. Some advice, don't tense up. That will only make things worse, as you noted yourself. Causing buzz will happen, it's inevitable. I'm in stage 4 of the beginners course and i'm getting buzz too from time to time. Move on, keep up the practice. It gets better in time. Also, i've noticed that a healthy mental attitude is key to a good practice. If something goes wrong, something's not working right, your hands aren't cooperating, no sweat. It will be better tomorrow. The big key thing here is: practice and having fun playing.
You ask yourself: why bother? I've told myself upon asking that question: because i love it. And that's all the motivation you'd need imho. Not going to play in a band? Fine. Still, i love what i'm doing. I don't care about much else.
As long as you love playing, the rest will come. Keep at it, keep a healthy mental attitude and don't dwell too long on the mistakes you make. (There will be many more.... XD).
Keep up the good work!