Help with finding free food - dumpster diving

I've been made redundant and I found out this week that I have £2 to live off for the next month after I have paid my rent. I'm currently waiting to hear back from the council about a food voucher and the food bank.

Does anyone know anyone who gives out leftovers or end of day food?

Also, does anyone know where is good to go dumpster diving in York?! I read that waitrose was pretty good but just wanting to know if anyone here does it or has done.

Thank you in advance.