Seems UK prices are a bit lower than here. We have just seen a small increase but they are now €18.25 for a 25Kg bag (standard size here) of Sanders layer pellets. Converting that to £ and a 20kg bag works out at £12.70. A lot depends where you buy them from though. The gardening stores are more expensive and if there are no competitors nearby, as was the case with an independent store in the Dordogne, you can pay double. You can also add €5 if you want to buy without chemical colourants, or 'yolk enhancers' as they call them.
When we left the UK we were buying Smallholder layers for under £7 a bag, 500 Kg at a time, but that was 10 years ago. The prices in the Dordogne came as a real shock, doubly so because we couldn't sell eggs without a business licence.