GP's are unlikely to KNOW who's entitled to free prescriptions especially with all the new rules that have come in with UC.
It's appalling and should be better publicised who IS entitled not least because then those who AREN'T would know too and not end up with fines for not paying.
Here in Scotland they're all free - I'm sure that's not only simpler, but cheaper all round and won't lead to people not treating conditions because they can't afford or think they can't afford the prescription cost.
Personally I wouldn't trust signs as you've no idea how long they've been up and if the info is accurate BUT no reason why people can't be directed to look it up on nhs website.
https://www.nhs.uk/using-the-nhs/help-with-health-costs/get-help-with-prescription-costs/
Though I think it's off that it's so difficult to find the right link on the UC pages on gov website!
Annandale 
So sorry for your loss. I fear he won't be the last affected so tragically by these changes.
You're not stupid. You'd need a bloody postgrad to fully understand the ins and outs of the welfare system! I could do a sodding PhD at this point!! It's an absolute minefield.
HundredMilesAnHour - the backs of prescriptions are hard to read for many and the information is largely inaccurate now but it would be too expensive to withdraw those already printed, not sure what the plans are for new ones with the new UC rules! Frankly you'd probably need a huge leaflet like the patient info leaflets inside the prescriptions!
Hallloumi just please be careful the rules seem to be changing constantly at the moment and I'm sure you'd hate to give a patient wrong info that caused them to get a fine.
It's crazy - it's more pressure on GP's and pharmacists and is already causing much confusion for many patients.