A massive source of single use plastics are shampoo and conditioner bottles. You can replace these with shampoo and conditioner bars.
A word of warning though, it may take a little time for your hair to transition to a bar. Some people are absolutely fine. This is nothing to do with the bar but, how often does your hairdresser tell you that you should be using shampoo and conditioner free from chemicals and sulphates? Most of the products you can buy in the supermarket or Boots are full of chemicals which your hair and scalp have got used to. If you are going to rid your hair and scalp of these chemicals, it will take a little time and patience but I promise that the switch is SO worth it.
Members of the Facebook page recommend:
White Light Candles with Karey (made in Pontypool)
Rush Organics (Bridgend)
Friendly soaps (available at the refill station)
Alter Native (available at the refill station)