There will be a flat 20p deposit on all eligible plastic and metal drinks containers. These deposits can be retrieved by returning containers to collection points at supermarkets.
The Welsh government want this to be devolved to them: https://exchangeforchange.co.uk/news/welsh-government-decision-on-exchange-for-changes-dmo-application/
That was a better scheme. That was only for glass bottles, as they were collected from the stores and reused.