By living in a country you "sign a blank cheque" for the government to tax you as it sees fit, sort of. "Tuition fees" were always a graduate tax by the back door. This kind of thing goes back to Thatcher looting the GCHQ pension fund back in the '80s. I would say "don't make a "contract" with the government", but even if you don't have a "contract" they can still decide they want to take your stuff.
Well you don't have to live in the country for them to decide you owe them money in other ways too. Both the "loan" and any other taxes or sanctions are only enforceable to the extent that you have assets in the UK.
