Hey there,
My DD was nearly 13m when she started nursery and went into a room with a one nap routine for three days a week. She was probably further on in the 2-1 than your LO (as in mainly on one nap), but it wasn't consistent. For the first few times she was there, I found they would actually put her down early if they thought she wasn't going to make it to the set time, which surprised me. And there are often LOs randomly asleep at other times. But even if your nursery won't do that, the things I have found helped the most are (1) making sure the nursery know how to settle her and have her comfort blanket etc for familiarity, (2) asking them to try to resettle if the nap is short, and explain how you would do that, (3) early bed time on nursery days, and (4) trying as much as possible to let go of the idea that routines will stay the same with different carers (hard I know - I am still a stickler for nap and bedtimes when it's in my control!). We have had some shocking days at nursery with sleep - as in a 25 min nap all day on at least three occasions, but I have stuck to our normal routine at home with early bedtimes as needed and it has worked out ok. Given she's only there two days a week, I think you should be fine
. Just be prepared for some longer catch up naps on home days - a nice side effect!
The one thing I would do is insist that she is not woken from her nap, unless its absolutely necessary (as in they are actually going out for activities). I think capping the nap if she manages to sleep that long is a bad idea in the 2-1 as OT accumulates quickly, and I don't think it's unreasonable that you request that. Another thought would be to ask that she is one of the first to be taken for her nap. Logistically they can't put them all down at exactly the same time, so I know in our case a set 11.30am nap is often closer to 11.45/12 - if she goes down first you might be able to keep the OT to the minimum possible.
Good luck, it really will be fine