Another year isn't really long in the grand scheme of things for a uni you really want, you probably have 30-40 years of career left so another year won't make that much difference time wise.
How much more will it advantage you to wait? Will a another uni give you better career prospects in your field? Do you feel you'd achieve a better grade at another uni? Can you use the next year constructively to get more work experience and save some money perhaps? All would be good reasons to think about to justify the year wait i think.
Edit: You could also see if there are any places in extra or clearing this year at a uni you prefer.