Question

Проверьтеиесли можнодополнитеиспользуя-saying what you are doing /did/are going to today we're visiting museum/relaxing this evening i am going to a restayrant /concert/ on a coach trip the shops the weather in london my favourite place dear kate i hope you are ok. i am in london with my classmates. london is a very beautiful city. we're staying in a hostel near london. we have been here since saturday and we have already, done lots of things. we have visited the tower of london, the british museum and madam tussaud's. it is very interesting travel. english people are friendly and polite london is very exciting city. it has a lot of showplaces. we visited big ben tower, british museum and other landmarks. i was very interested by sherlock holmes museum. i like to walk among the students of cambridge or oxford university in their campus and to imagine that i am one of them.

Answer 1

 "We've been here" avoids the use of the word "since", which seems to cause a lot of translation problems although that's a correct form... a lot of things... at the end: imagine, not TO imagine

Answer 2

Dear  Kate,

  Hi! How are you? I hope you are ok. I am in London with my classmates. London is a very beautiful city. We're staying in a hostel near London. The weather here is sunny and hot.   We have been here since Saturday and we have already done lots of things.  We have visited the Tower of London, the British Museum and Madam Tussauds. I also went shopping. The shops are really huge! People here are friendly and polite. London is a very exciting city. My favourite place in London is Sherlock Holmes museum. I was really fascinated by it. I like to walk among the students of Cambridge or Oxford University in their campus and imagine that I am one of them.

Well, I have to go now. The phone’s ringing! Hope to hear from you soon.
All the best,
[твое имя]