Comparisons-
U.S. fees and tuition is as low as $5000 for some state schools to as high as $50,000 (higher for medical schools). An "average" is about $27,000.
Add cost of living, $5000-14,000.

Example for a good state university, Wisconsin- $11,000 for state residents, $26,000 for out-of-state.
Private schools like Harvard, Princeton are about $38,000; California Institute of Technology, $36,000.

18,000 pounds would not be considered unusual for a good U.S. school.