All the above advice for accompanying on English seems to have worked for those I've observed. In Danny Spooner's case it took him quite a while. In the '70s he just did the sorts of chords he would have used on his guitar, with no fancy changes but he's been exposed to lots of melody players and gradually picked up confidence and competence. The players I've seen seem not to have noticed any problems of the instrument interfering with their ability to breathe, possibly because the bellows can be manipulated to accommodate one's own breathing. I can't say for sure because I'm yet to come to terms with the English keyboard.

Anglo is a different matter, however. Because I started playing on a 20 button instrument I was restricted to playing in its native keys and I never did like singing much in C. When I got a D/G Crabb I was still playing up and down the rows and found that the requirement for rapid ("random"?) changes of bellows direction to be a major hindrance when wanting to sing with it; its breathing was quite different from mine so I stuck to mostly dance music. However, perseverance pays off and now I'm quite happy singing with any number of songs. Perhaps the first song I 'caught' the ability to accompany myself on was "Two little girls in blue" and I suspect that it helped that it is a gentle waltz.

I can't support the advice for sticking to chords on an anglo but that's just because it didn't work for me as I'm mostly a melody player. If it works for you, grab the ability with both hands.

Cheers, Rowan.