Lee there are over 7000 tax rules at the moment and they are growing each year, its your accountants job to know these and to use them for your business.
You could try and get though them on your own, you can even phone up the revenue for help, but remember they will only give you simple answers to your questions, they don't know your business as well as a accountant does.
The other thing you need to look at is what happens if you get a tax investigation, these are decided mainly by the revenue's computer, so you can be as honest as they come with you tax returns but you will still get an investigation, allthough a accountant will not make the tax man go away, you are more likely than not to make less mistakes with one.
But it all comes down to personal choise, I have a chartered accountant and I pay him £350 a year, but I clean his windows and charge him £325 per year, so I'm getting someone who does all my staffs wageslips, plus he sorts all the paperwork and files my returns every year for £25
