1. Classic FM has a whole section devoted to music for babies, including a list of five pieces it recommends for them (mostly slow, calming music so they don't help with my tidying but perhaps could help in a bedtime/nap routine). It does also use this section to plug an album of "50 Classics for Babies", which, unsurprisingly, is available for purchase. I can't say I've bought it myself, but if you are new to classical music and would like a collection "calming pieces" it could be somewhere to start.
2. Baby Einstein has some videos on YouTube set to classical music. My son hasn't seen these yet but my daughter loved them when she was younger. The one below is Baby Mozart, but there is also a Baby Bach.
I am not suggesting these videos are educational... I am suggesting they are less irritating than many other children's programmes because at least the music is good. If you are always able to devote 100% of your attention to your child then don't use them. For anyone who's like me who occasionally has to abandon their non-self-entertaining child for a few minutes while they cook/clean/wash, these videos could be helpful.
3. Your operating system's app store has loads of "music for babies" apps, free or otherwise. I haven't actually downloaded any, preferring to make playlists from the music I already have, but they could be another place to start if you have little music already. If you have any recommendations for apps, do post them in the comment section below.
4. Other suggestions?