@eggsbenedict23 and others: Mumsnetters on this thread may also find it useful to know about the American category called elite four years colleges. We do not have anything comparable in the UK.
Example include Amherst, Swarthmore, Oberlin, Williams, Reed, the Seven Sisters, the Claremont Colleges, etc. Some are nearly as competitive as the IL. I mention them because some - Amherst comes to mind - offer good aid to international students.
The academic staff are superbly qualified; they have simply chosen at some point (in STEM nowadays, typically after postdoctoral work) to specialise in teaching rather than to combine teaching and research. These colleges do not offer PhDs or, therefore, exposure to PG modules as a UG. But class sizes are smaller, all teaching is done by dedicated staff (where the Ivies, like all research universities, use PG students for discussion sections) and chances for UG research abound. The education is recognised as being second to none. Doors to PG study and employment at top institutions are wide open. Colleges tend to work hard to place their UGs as there is no competing PG focus. Alumni networks are strong.
On a thread within the last year or so, a MNetter said she’d had one DC at Oxbridge, one at an Ivy and one at an American four year college. The college student had the best experience.
If your DC is considering study in America, the top four year liberal arts colleges - which definitely offer science and may or may not offer engineering - are worth a thought. You can search online for lists of those providing parity of aid to international students.