I contact sainsburys asking mainly about there seasonal stock, and here is the response seasonal tradition get back.
Thank you for your email. We appreciate you taking the time to contact us. We are always happy to answer enquires from our customers.
After looking into this I can confirm that we do not currently have information regarding our fireworks, Halloween or Christmas stock. With that in mind we would request that you contact us nearer the time so that we can see if we will be able to provide you with the information.
If you do have any further questions in the meantime please do not hesitate to get back to us and my colleagues will be happy to help.
We appreciate you taking the time to contact us and hope to see you in store soon.