You should also check out getcoconut.com - it’s a Monzo-like account specifically for freelancers. At the moment it’s in beta, so you can categorise all of your expenses (in HMRC categories) and it will tell you how much tax you’ll need to pay for the financial year. However they’re building invoicing as a feature and it’ll directly link to HMRC for tax returns, or export to an accountant, in the future too. Monzo have suggested it as a good business bank account to use when previously asked about freelancer features.