I spent an hour or so looking into this recently, and couldn’t find any DAFs that were suitable for small donors. It’s possible I missed one, though.
CAF offers a ‘giving account’, which is effectively a low-interest savings account. You can get immediate tax relief for deposits, but forgo returns, and can only donate to UK registered charities, so seems like a weak option: https://www.cafonline.org/docs/default-source/personal-giving/2573h_charityacc_web-app_pdf_220519.pdf
FWIW my tentative conclusion was that the best option for savings small-ish sums for giving later is a straightforward ISA. You don’t get any immediate tax relief from paying into the ISA (you’ll get this when you donate the money to charity) but you do get (tax-free) growth, and retain flexibility in when and how the money is donated. Returns are important if you think you might wait a long time before giving, flexibility seems important if one’s motivation for giving later is the possibility of some high-leverage opportunities in the future. The main downside is that you can’t easily bind yourself into future donations this way, but I thought this was outweighed by the other factors in my own case.
Yes that’s what I meant—will edit for clarity