I was thinking that an answer to youth unemployment and graduate underemployment would be a career scrappage scheme. With personal and defined contribution pensions being so poor for the whole of this century I think the government should match the individual's contributions or savings in turn for an obligation to live off savings or pension and not take employment. There probably should be a sensible cap in the region of GBP 80,000. Also maybe not even match, but give people some money into a pension anyway if it will be enough to not claim benefit.
So far so good, but what happens if there is an opportunity for work that seems too good to turn down? This could be checked with HMRC and national insurance contributions, putting national insurance charge of say 80% on earnings, (or tax on dividends if you get paid that way.) As regards working in non-UK locations, if you emigrate then I think the government's tentacles only reach so far for British citizens.