Thanks for your responses, all.

JimmyT, I would see it as a fair exchange rather than a donation, but I suspect that they might see it as a free performance - and a bad free performance at that, if I end up using the practice time to learn something new rather than just keeping up repertoire. I've talked a lot to Genie and Musicmic here at Mudcat about the business of nursing home gigs, and they insist that playing for free is a good way to not get hired.

Treewind, not exactly; my set is mostly vocal, guitar, and fiddle, but I'd like to be able to throw in a few piano pieces for variety. So I just need to keep a few pieces ready, and if there's no piano in the room where I perform, I can just skip it. So I don't see a need for daily practice or my own instrument.

Cheers, Marion