It really does depend on the school; more than that, on the particular teacher you happen to get.
Reception probably won't be so much of a problem because they only do phonics in very small bursts. Year One, when the academic teaching really ratchets up, is when it can get a bit more tricky, but we had an amazing teacher then who would search out the right books for DD and talk to her about them once or twice a week.
As for phonics, it really does depend, again. DD's school streamed years 1-3 all together and so she was in the top group, doing more writing and spelling than phonics learning, from the start. You may get lucky or you may not.
Do you have a choice of schools? If so, start asking generic questions about how they deal with this now (i.e. not my child is amazing, but how do you deal with this when it happens - some teachers told me it had never happened in their class before).
Can you also not look at another nursery for next year? DD's Montessori did a much better job of teaching her at the right level than school did and we would have quite happily left her there for another couple of years if it had been an option.