Companies House
Search for any Ltd companies or find if your new company name is available.
https://www.gov.uk/get-information-about-a-company
ICO (Information Commissioner's Office)
It is mandatory for all individuals and companies who collect any form of customer information/data in the UK to register for data protection with the ICO.
https://www.ico.org.uk
GOV.uk
UK government website for information about VAT, PAYE/NI, Corporation Tax and business setup.
https://www.gov.uk
IPO (Intellectual Property Office)
UK government website for Intellectual property, Trade mark, Patent and Copyright information and registration.
https://www.gov.uk/government/organisations/intellectual-property-office