Wow, it sounds like you are having a really hard time with this.
I understand more about what you mean now about topics, cross posted earlier, and I think you really do need to know more directly from the nursery.
In the nursery I work at, just to give you an example of how we plan, we decide at the start of each term what 'topics' we will cover and we choose some focus books, as well as leaving some weeks free of any topic so that we have time to be a bit spontaneous and respond to the children's interests. What and when we cover these things are free for us to choose, and as long as we provide for the 6 areas of learning and development that I mentioned earlier, we can do what we want.
So we might choose a book which will be read most days one week, then choose different activities connected to it. Like if the charachter is eating a certain food we will cook it, or if it's about aliens we would get the space toys out. We do more than that, but this is just to give you an example.
It really wouldn't be very hard for us to give you the information you want for these pre planned weeks, especially when it comes to things like religious or cultural festivals that we inted to cover. After all, the dates for them are known!
I think you need to talk to the nursery manager SENCO or your child's key worker and reinforce how much your child will benefit from this information. They are obliged to work in partnership with you on things like this, so don't take no for an answer, and don't worry about increasing their workload. It really doesn't need to give them too much extra work, and that is their problem anyway, it's certainly not your's or your ds's problem.