Average student debt is £53k (~$71k USD): https://commonslibrary.parliament.uk/research-briefings/sn01...
Given the disparity in middle-class household incomes between the UK and the US, I suspect a majority of UK middle-class students would be eligible for some form of financial aid from US universities (assuming Oxbridge vs US equivalents with need-blind + full-need international admissions), meaning their net cost to attend could be lower than studying in the UK.