Cambridge english Writing and Improve

I started practising English by using Cambridge English Write & Improve. There is a few feedback but I do not know to reach B1 level. My level is always A2. (But my actual English level is B1, I believe)

So here is Theme of Writing.

You recently went on a trip for two weeks. While you were away, your friend, Ken, looked after your home. When you return, you decide to write an email to Ken. In the email:


thank Ken for helping you
tell Ken what you did on your trip
suggest a time to meet Ken.

Write about 90 words.

And my writing sentences are...

Hi. Ken.
Thank you for looking after my house for two weeks.
My trip was so nice. I started my journey in Paris and moved to Germany and Czechia. Then, from Poland I returned to Japan.
I visited some friends in each country and hanged up. There are very beautiful places, but Prague Castle impressed me the most.
That castle is in Prague, Czechia. The building started in 870 AD which means that  the oldest part of the castle is over 1000 years old.
I bought some souvenirs for you. If you are free next Monday morning, let's hang up.