You may find the following links both relevent and useful:
Firework Safety
https://www.saferfireworks.co.uk/over-18s/
Firework & Pets
https://www.bluecross.org.uk/advice/pets/wellbeing-and-care/fireworks-and-pets
Selling, storing, organising a fireworks display.
https://www.hse.gov.uk/explosives/fireworks/index.htm
Manufacturing and Storing
https://www.hse.gov.uk/forms/explosive/exguide.pdf
Fireworks in shops
https://www.hse.gov.uk/pubns/indg407ch.pdf
Firework Safety & the Law
https://webarchive.nationalarchives.gov.uk/ukgwa/+/http://www.direct.gov.uk/en/HomeAndCommunity/InYourHome/FireSafety/DG_064665