You have arranged to visit a friend in England but an important event at home now means that you must change the dates of the visit.
Model Answer
Dear Albert,
Hope you are doing fine. I have been eagerly waiting to meet you in a few days and spend some pleasant time in England. However, my younger sister gave birth to a baby boy two days ago and would be staying at our home for around 3 weeks. I am afraid I will have to reschedule my visit to England in early June instead of early May.
I have almost finished my preparation to travel to England and applied for the visa. If things go as expected, I will get the visa in a week. Despite my anticipation to meet you on 3rd May, my current situation forces me to delay the tour for a month. My sister has had her first baby and she is staying with us. We are so happy to have a new angel in our family and my presence is quite important for the baby and the mother. I am the only male member of the family and cannot desert my family while I travel to England.
I am so sorry that I cannot visit you as initially planned and it must be hard for you to reschedule everything. I wish I have had an alternative!
Wishing to meet you on 4th June if everything goes smoothly.
Take care and have an excellent time ahead.
Warm wishes,
Jonathon