It's fascinating hearing everyone's advice and experiences!

I think I'll probably mainly want (when I'm good enough) to play along in sessions, not to play solo very much; so it's probably better if I learn to finger tunes on both sides of the instrument, with maybe just a little harmony here and there.

I hit a problem with the 'breathing' in some tunes; for example, in 'Drink to Me Only' there's a whole line that uses pushed notes only ('The thirst that from the soul doth rise')! I know that when I improve I'll be able to find equivalent notes on the other side to avoid the problem; but at the moment, my concertina has to take a massive 'breath' at the end of such line, which kind of spoils the flow of the tune!