I have already had a few queries about accessing the Google Classroom. Below is a link to a blog we did earlier in the year to get you started.
There is no need to enter a class code as the login username and password that you have been sent will automatically take you to the correct classroom. I have put everyone into the same class, called Year 2. You may also be able to see 1M or 1C listed, but these should be gone by the end of the day.
If you still receive and an error asking for the class code it suggest that you are already logged in to another Google account. You can either log off that account to access your Google Classroom account or open an ‘incognito window’, which is an option in most modern browsers.