You might find the following links useful:

www.accaglobal.com
The Association of Chartered Certified Accountants

www.hmrc.gov.uk
H M Revenue & Customs

www.companieshouse.gov.uk
Companies House

www.businesslink.co.uk
Business Link

www.berr.gov.uk
The Department for Business Enterprise & Regulatory Reform (The New DTI)

http://business.iris.co.uk/accounting__business_manageme.aspx
Iris Business Software

www.sage.co.uk
Sage Accounts Software

http://quickbooks.intuit.co.uk/index.jsp
Quickbooks Accounts Software

www.microsoft.com/uk/smallbusiness/products/
office-accounting-professional-2008/overview.mspx
New Accounting Software from Microsoft