kindly make corrections to improve me...thank you in advance

It is a letter writting task.
You arranged to visit a friend in England but an important event at home now means that you must change the dates of the visit.

Dear Jenny,
I hope this letter will find you in good shape. I am writing to tell you that I unfortunately will not able to come to your place in August as planned earlier. I was requested to attend the 50th anniversary of our school at a very short notice and it would be wrong to avoid the occasion. I regret for ruining our plan and I am sorry for that.
However, I was thinking of flying to your place in September after the school opening anniversary, with my daughter. So, I was wondering if you can spare some time of a week during that time and I could book the ticket accordingly as soon as possible.
I look forward to hearing from you on this and I can’t wait to see you after ages.
With (warm or kind) regards (or With love),
Karner