Dear Mary,
I'm writing to tell you that I'm going to visit London next weekend, and I'm very excited now. I'm planning to go to some famous landmarks in this city like the Tower of London and the London Eye. Moreover, I'm also going to take part in a local festival here to write a report for my blog. Are you free at these time? I hope that we will have good time there.
I look forward to hear from you.
Love,