Here is a list of websites you may find useful;
HMRC – www.hmrc.gov.uk
Companies House – beta.companieshouse.gov.uk
Department for Business, Energy & Industrial Strategy – www.bis.gov.uk
Health and Safety Executive – www.hse.gov.uk
Companies Act 2006 – https://www.legislation.gov.uk/ukpga/2006/46/contents
Start-ups – www.startups.co.uk