I've been going to various cities to freshers/welcome week fairs for years. You always walk in there is never anyone asking to see student I.D. There are often beer bottles, toilet rolls, posh barbecue sauces,t shirts, soft drinks, energy drinks, Dominos pizza all being handed out for free often in large quantities. Also vouchers, which many people drop on floor/leave on tables, for the next few weeks or months for free drinks at all kinds of independant and chain bars and restaurants, cafes for completely free food and drinks. Wetherspoons booklets full of vouchers to use anywhere in UK until November.
Can be a bit hard to discover when and where exactly these events are held, but will all be between now and early October.
in Manchester both universities hand out dominos pizza hot and freshly made. at the academy on oxford rd for Manchester University, there are tables with literally hundreds of large pizzas being brought in all day. you can go back whenever you like. the vouchers they give out have vouchers for free pizzas at future dates.
Example in link is MMU in Manchester, 21-22 September.