For those on iOS, I highly recommend the app Copied. This will solve all your account number woes, and many more. Create a custom list with your account number and sort code, and you can use its keyboard to insert them directly when setting up the daily direct debit. Much quicker and more convenient than manually typing from a card each time.
https://community.monzo.com/t/custom-categories-1/649/108?u=jzw95