great spot! and there is currently a 5p saving. ha haAmazon has a 50 ltr bag for £12.95, delivered to your door.
https://www.amazon.co.uk/Hydrogarden-Canna-Coco-Coir-Natural/dp/B004WY128O
With any luck Poundland will be stocking those small bricks of coir again this year. I brought several last year & still have most of them still sitting here, but a few more would be helpful.
I think I may stock up at that reduced price.