Answer
It is an offence to:
possess adult fireworks (all fireworks except category 1 fireworks - party poppers, sparklers, throwdowns etc.) in a public place by anyone under the age of 18;
possess category 4 fireworks (professional display fireworks) by anyone other than a fireworks professional;
it is illegal to supply adult fireworks to those under 18;
throw or cast or fire any firework in or into any highway, street, thoroughfare or public space (this would include throwing or firing from a private place into a public place, street, highway etc.);
to light any fire, or permit a fire to spread to, within 30 meters of a road which causes damage to the road or endangers road users.
to light a fire in a public place so as to endanger any other person or give them reasonable cause for alarm or annoyance or so as to endanger any property.
There is a curfew on the use of adult fireworks between 11pm and 7am, except on:
Bonfire Night (when the curfew is between 12 midnight and 7am);
New Years Eve (when the curfew is between 1am and 7am);
Chinese New Year (when the curfew is between 1am and 7am);
Diwali Night (when the curfew is between 1am and 7am).
The penalties for using fireworks outside the above curfew hours are imprisonment (maximum 6 months) and a substantial fine. Please note, you could also commit offences if they were being used to cause a nuisance.