From the 31 March 2021 the use of metaldehyde will be phased out over 18 months to give growers time to adjust to other methods of slug control. It will only be legal for manufacturers to supply metaldehyde products until that date. Onward sale by distributors and use of the products will then still be allowed for a further 12 months until 31 March 2022.
You can read the statement from DEFRA here https://deframedia.blog.gov.uk/2020/09/21/ban-on-the-use-of-metaldehyde-announced/
