Answer:
Cross out did before invited
Comma after yesterday
Add "-ed" after visit
Add "-ed" after tour
Add "-ed" after watch
Add a comma after later
Cross out 'are'
Our corrected sentence should look like this;
Hello from London. Our friends invited us here for a week. Yesterday, we visited Big Ben, and we toured Buckingham Palace. This morning, we watched a cricket match. Later, we walked around Piccadilly Circus and enjoyed coffee and sandwiches at a cafe.
