Party Animal,
I was in the same situation as you for the last 3 years. I have kept my own records and filled in the self-assessment forms myself with ease. I haven't had an accountant and I'm not convinced they would help much. You basically add up the income, take away the allowable expenditure (mostly correctly identified above), then split the "profit" between you and your wife. If your wife has no other income, she'll be well below her threshold - HMRC told my wife to not even bother submitting a tax return. You'll then pay tax at 40% on your bit.
There are leaflets online describing what is/ is not allowable expenditure. I thought it would be a good idea to pay my wife to do the books/ repairs/ manage property etc to use her full tax allowance- but you can't do that if she is a joint-landlord. You can claim expenses to make visits to the property but HMRC are wise to landlords making multiple visits to overseas rental properties to make 'repairs'!
As a guide, we have a property letting for a similar amount with a similar mortgage (albeit the interest component is only roughly 250) and with only a few small repairs per year, I end up paying around a grand in tax per year.
That said, many of my friends pay no tax and some own multiple properties, so perhaps I do need an accountant!