Cash is legal tender here, too, but NOT banknotes and (in small denominations) only up to a limited amount (I can't remember the details but you can't insist on paying thousands of pounds in pennies). Pound coins are legal tender for unlimited amounts and, as in Canada, must be accepted.
However as I understand it clubs and businesses are free to offer differential pricing for different payment methods (in advance - they can't change the rules after invoicing) which makes that all a bit meaningless.
Having spent four years as a volunteer treasurer of our Common Room I sympathise with all the above comments, though we were able to collect subs through payroll which was simpler still.
Tim
PS see
Legal tender - Wikipedia, the free encyclopedia