I do think you were being a wee bit optimistic if you've only got one settling in day but that's neither here nor there PLUS nobody tells you these things, right??
I didn't go back to work until my DS was nearly 10 months and he, like yours, refused a bottle so I was really anxious about would he be thirsty, what would he do, should I go & nurse him midday... plus we did BLW (yay!)and the CM had never heard of it so I did her a sort of briefing sheet about it. I also didn't get too stressed (ha ha! okay, I tried not to, anyway) about how he took in food when he was in her care as long as he was eating; I didn't see it as her job to absolutely replicate all of my parenting choices and frankly, I didn't want her to try.
So... to mitigate this, we got him drinking out of a Doidy (those slanty) cup and through straws, and she was fine with supporting that - there are loads of options in the bigger shops for cups.
At first I really wanted to go and nurse him midday but realised that it wouldn't be fair on him or the overall setting - there was another little girl, slightly older, who got very upset when I collected my DS and always began weeping for her mother - this stressed out my DS and probably the CM. Plus after a few days he didn't seem to mind - he learnt to nurse the heck out of me when we got home but also started weaning towards night & more pigouts and within a month wasn't really nursing in the day much anyway (he nursed until he was 2 with little night/morning feeds so it certainly didn't interrupt our nursing).
Also with the BLW I sent easier stuff - so not the "hardcore" stuff like carrot sticks, etc. Again - for me, I wanted to be sure that he had 100% attention when he was negotiating tricky foods and so I left that to when he was at home & sent slightly squooshier stuff along for his lunch because I wanted to find a flexible way forward that didn't ask too much of her but still fitted into our family's style of parenting & food.
I hope it's all going well so far!! Just wanted to reply to show that it can work but also to show the CMs on here that some of us parents with particular parenting styles can be very flexible & work in partnership, too!