A long and hard road indeed. You can't apply for residency at all these days unless you are earning over £35000 so are stuck paying thousands every few years. And at any of these they can say "Toddle off now" so building a life is really hard. If you get residency and pay the sort of figures you mention then you have to go through tests like these. The incentives to be illegal are massive, especually for those on minimum wage.