You need to complete 3 more modules for you to carry on driving after your current card expires next month. No you don’t need to wait for your card to arrive, you can carry on once you’ve completed the 35 hours.
Once you complete the 3 more your new card will expire 5 years later than your current card if you complete the last module before the current card expires or from the date you complete your last module if after
A module has a 5 year limit for you to use it in a set of 5, so if you stopped driving but returned in 10 years say, then the 2 you’ve currently done but not use would have expired and you’d have to do 5.