Here are some links to other sources of useful information

Business guides and information
HMRC Youtube channel for guidance on many aspects of Self Assessment, VAT etc.
Setting up your own business - what type of organisation should I use?

Taxation
Check if you need to complete a Self Assessment tax return
Income tax rates and Personal Allowances - current year, previous years
Who should register for VAT?
Company tax rates and reliefs

Pensions
What is Automatic Enrolment?
How much might I get in State Pension - calculator

Employees
Basic rights at work - guidance from the Citizens Advice Bureau
Useful templates for letters, forms and checklists - free from acas
Discrimination: Your rights
Controlling risks in the workplace - guidance from HSE