More time posting than coding
Contractor accountants should be about £85 + VAT a month (e.g. Gorilla Accounting, others are available) and that includes the Freeagent web based accounting software which alone is £29 + VAT per month if you buy it direct.
That, IMHO, is a small price to pay to not have to come onto an online forum and ask accountancy questions, the paperwork is probably more intensive than you are expecting.
You'll find there are other expenses which you haven't thought of (mobile phone, "use of home as an office", insurance, christmas party etc), the tax savings on all that will pay for your accountant.