Preface: I'm only vaguely familiar with UK corporate law and finance ...
... but unless book-keeping in the UK is vastly different than book-keeping in the US or you are not making enough money to justify the expense, it is always best practice to work with a certified public accountant.
If you do decide to incorporate, I'd get free consultations with a few local accountants and lawyers. These consultations will consist of you telling them what your needs are. As with all sectors, there are predatory accountants and there are good accountants. Find one that is within your budget and feels right to you. By "feels right," I mean that you should avoid dealing with individuals or corporations who try and hard sell you or who speak to you condescendingly. This is a common experience for new business owners as the remuneration for small accounts is minimal at best and in many cases you'll be dealing with account managers (professional sounding name for a salesman) who eat off commissions and not the accounting team themselves.
Luckily, small accounts are the bread and butter of many smaller accounting firms and they are often willing to scale their rates based on your needs. It should also be noted that unless your operating at a high volume and have a large number of transactions, invoices, expenses, etc that you need to account for, you can generally get away with seeing your accountant once every month or even every other month. These meetings are generally very brief and consist of you bringing in a folder of receipts and invoices, saying, "Hello," relaying any concerns or peculiarities, shaking his/her hand, and leaving.
While, as jammie said, one can certainly learn the basics of accounting through books or night classes, there is a reason why accountants get the education that they do and are tested to the extent that they are; real accounting is complicated. Beyond being able to call many extremely successful accountants my personal friends, I've also had a lot of experience in both starting and growing new businesses. When I first started, I wanted to do everything myself for a lot of different reasons, not least of which was the cost. What I quickly discovered after taking the leap was that accountants tend to pay for themselves in one or two events over the course of any given year. Even if you get a BA (or equivalent) in accounting, in 9/10 cases you won't be as familiar with business accounting as a working accountant with 3-4 years of experience under his/her belt.
I could talk about this topic for hours, but I guess what I'm trying to say is that I would never go into a new business venture (again) without first protecting myself by bringing the proper people on board. If you don't do it now and you end up staying in business for 5 or 10 years, you probably will then. There are people that will disagree with me and that's fine, but developing strong, long-term relationships with experts is a significant part of doing ANY kind of business successfully.
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