You’re definitely a winner, Thomas - couldn’t have timed it better! 
We’d absolutely love it if you were to start using Monzo as your main account! We’re still working on offering full statements, but in the meantime you can export your transactions from the app into a CSV or QIF format. If you need proof of account ownership, we can sort that out for you - just give us a shout through the in-app chat 
There’s no harm in keeping your existing account with HSBC open, especially if you’re moving soon! As a few others have suggested, you could even keep it active and empty, and still use Monzo as your main account. We only run a ‘soft’ credit check when you open an account, and this leaves no digital footprint - you’ll have had this check done already when you opened your account.
We don’t support international payments yet, but it’s definitely something we’re looking to implement.
There’s no pressure, though! If for now, you’d like to continue using the current account in the same way you’ve always used the prepaid card, that’s cool! Do what’s best for you, and if doing that allows you to use Monzo as your main bank, then that’s all the better 