I would highly recommend you looking at Xero. This is software built for non accountants and is fantastic. It's easy to use cloud based accounting software which can integrate automatically with your online bank account to post the bank transactions into Xero for you directly from your bank saving a lot of time and hassle on your end. It can produce P&L,balance sheet, aged creditors/debtors reports and vat returns. You can also email your invoices and using paypal for example your customer can click on the emailed invoice and pay you directly online.
Additionally as it is cloud based there is no software to install, no backups and updates are done automatically. It doesn't have payroll built in but for that you could look at another cloud based payroll software mypaye.
Xero will cost £20+vat per month for their medium package which is their most popular but we have a lot of clients using it and it is great value for money. It can also integrate with over 300 other online add ons such as CRM so as your business grows then you can look to use these too to help manage things better.