You could follow up with a brief one along the lines of
"Thank you for sorting the dancing class thingy. Just wondered if we could agree the weeks for Easter now please. I'd be grateful if we could agree the Easter holiday weeks please. If I don't hear otherwise within the next couple of days, I will take it as agreement that I am having the second week from Friday xth date, as I proposed on x date"
Not "thingy" obviously - I just wasn't quite sure what it was. Also the last bit might need amending if you didn't propose the second week last time. But that is basically saying - no reply means agreement to what I have proposed. That sometimes gets a response! If you still get no response then send a low key solicitors letter so it doesn't come across as confrontational, maybe saying - we need to confirm arrangements for the childrens time over the Easter holidays with each parent, as per the Child Arrangements order. Our client proposes collecting the children on Friday xth at x time and returning them on Friday xth at x time. Please confirm that you are in agreement with this.
"Thank you for sorting the dancing class thingy. Just wondered if we could agree the weeks for Easter now please. I'd be grateful if we could agree the Easter holiday weeks please. If I don't hear otherwise within the next couple of days, I will take it as agreement that I am having the second week from Friday xth date, as I proposed on x date"
Not "thingy" obviously - I just wasn't quite sure what it was. Also the last bit might need amending if you didn't propose the second week last time. But that is basically saying - no reply means agreement to what I have proposed. That sometimes gets a response! If you still get no response then send a low key solicitors letter so it doesn't come across as confrontational, maybe saying - we need to confirm arrangements for the childrens time over the Easter holidays with each parent, as per the Child Arrangements order. Our client proposes collecting the children on Friday xth at x time and returning them on Friday xth at x time. Please confirm that you are in agreement with this.