Jon,I didn't mention playing across the rows because john c said he was a beginner. The lack of a C# on a two row C/G would also be a problem.
Wildlone,
I'm not an expert, by any means, on anglo concertinas. If you're interested in finding out more about your instrument, I'd suggest contacting www.hobgoblin.com. They are both experts and enthusiasts, and I'm sure an email to them describing your instrument clearly would get a decent reply.
Ed