Tide is a new kind of business account designed for small businesses, it's incredibly easy to sign up (takes under 3 minutes), you immediately get a sort code and account number and you can set-up sub accounts too (so say one is your main business and one for consulting). A card arrives a couple of days later which can be used in ATMs, stores and on the web to pay for things.
As posted before there's an invoicing part of the app and the template can be customised with your logos etc and then if it gets paid, it will tie the payment to the invoice, if it isn't paid, the invoiced person can be automagically reminded from time to time.
All transactions can be tagged (like Sales, Loan, whatever) so easy to see what's happening with your money.
If you haven't signed-up, do it now.
p.s. there are no bank charges as such, though some transactional fees will be taken (like in future when accepting card payments through the app).