The bag tax is 10p [1]. California has had a similar one since 2016 with a 10 cent fee [2].

Anecdotally, the fee seems to work well in both places, or at least single-use plastic bag use seems relatively low as most people seem to bring a reusable bag or use a backpack or similar.

[1] https://www.gov.uk/guidance/carrier-bag-charges-retailers-re...

[2] https://calrecycle.ca.gov/plastics/carryoutbags/

Yes, but the reusable bags seem to have become less durable and there has been a huge increase in the number of them used and therefore the amount of plastic used.

https://assets.ctfassets.net/bffxiku554r1/4TNPmg4tzrgoH39Iev...