"I've heard such a lot about these, how do i get one?"
Just go on your bank's website / phone app, and there will be a special link to apply.
For some reason Barclays hide the link so it's hard to apply. Recently Barclays were taking two hours to answer the phone, so it's not for the faint-hearted. Call backs take around 3-4 MONTHS (yes really)
Unfortunately not all banks are approved for the scheme (why do they need approval??), so your bank might not be processing applications. e.g. Metro 3rd June STILL hadn't got its act together. For the list of current approved boys see here https://www.british-business-bank.co.uk/ourpartners/coronavirus-business-interruption-loan-schemes/bounce-back-loans/current-accredited-lenders-and-partners/
Apparently you can open an account at a bank that offers bounce loans, and then apply for one. BUT regrettably many banks are refusing to open new business accounts at the moment. And remember you need sales last year of £200k+ to get the full £50k. PS. they take your word for it on the declaration.
Don't apply if your company was formed in 2020 as they only lend to older companies.