Ian, I use FreeAgent software. It's brilliant. You can do quotes and invoices, report RTI to HMRC and do your payroll. It also keeps you on track with how much corporation tax you owe. It's very simple to use and is cloud based software so no worries about updating and backing up.
I can provide you with a link for 10% discount, I mean both me and you get the discount
Also if you get 10 people to use it, it becomes completely free for you! Your No 9