She would be classed as an Overseas student, for at least 3 years, and I think you already appreciate just how expensive that is, compared to the level of Home student fees.
Do appreciate that the above is not based upon her nationality or visa status. That is, let's assume, and I appreciate these are not your wife's facts, but had she been born in the UK, and thus be a British Citizen, but let's say she emigrated to the US as a child, with her family, and has lived a number of years in the US, and now she moved back to the UK earlier this month, she would still be classed as an Overseas student for at least three years.