UK student accommodation depends on the university but generally there is university-provided accommodation for first years (mainly single rooms in halls of residence, a small number of double rooms in halls, and some shared flats with single rooms for around 6-8 people). Second years almost always live out in house-share that they organise themselves. Third years may have the option of moving back to university accommodation if there's enough space.
Class needs some clearing up. Kate Middleton, for example did not marry into the gentry - she married into royalty. Officially there
Royalty - kings, queens, princes, royal dukes.
Aristocracy - hereditary titles, but slightly lower down the ranks. Non-royal dukes, hereditary knights and baronets. Note that non-royal titles (particularly the non-inherited ones) can be awarded to anyone for service to their country so aren't necessarily a class indicator if they are first (or only) generation.
Upper class - what was formerly known as the gentry or landed gentry, because they had land to give them enough income not to work but didn't have titles (although there may be a bit of trickle-down of Honorables). Because of the inheritance and expense of upkeep problems described above many of them don't have the land any more but usually still have enough family money floating around for the odd trust fund or at least an expensive education and some subsidy from parents afterwards that makes it easier to get into jobs that require long unpaid internships or low paid training, such as the bar. The alternative is that they've kept the land but have no money beyond the bare minimum to keep themselves in gin and labradors. Tricky to define, but hard to to move into this class, it's certainly not a 1-generation step.
Middle class - divided into at least upper middle and lower.
The line between upper and upper-middle is pretty thin unless you are a close observer. Again they tend towards private education and jobs like barristers or the higher ranks of the civil service.
Middle-middle - probably the largest class, huge spread of school types, jobs and incomes but usually university educated. Very easy to move around the boundaries of this class and across into the other sections of the middle class in terms of job and education, but for those who care there will be speech markers that give away the exact strip of this class that you grew up in. Toilet, loo, or lavatory? Settee or sofa? Lounge, living room or sitting room (drawing room probably boosts you up into upper class unless it's a points deduction for trying too hard)? Napkin or serviette? Supper with friends or in your pyjamas? Afters, dessert, sweet or pudding?
Lower-middle class - harder to spot the non-linguistic clues these days, now that there's not a simple university or polytechnic divide and 'office work' is such a broad category. In terms of new socioeconomc classification I think this is C2, whereas middle-middle is C1. Traditionally probably the lower levels of office work, or manual trades that need a high level of skill and quite a bit of further/continuing education such as gas engineer.
Working class - trades that may still need quite a lot of skill but of the sort you can pick up primarily on the job rather than needing to go to classes and take tests - mining and factory work are the classic examples. In the service industries maybe reception and shop-floor work, non-celebrity hairdressers. The switch of the economy from one to the other left a lot of unemployment in this class, particularly older members and those in areas that relied a lot on heavy industry. The old view - or the current one if you're a politician or a Daily Mail writer - would assume this is the class represented by the 'deserving poor'. Movement from here to lower middle isn't too difficult, but further than that is getting increasingly hard as higher levels of education get more expensive and lots of jobs are closed to people without degree - not because the job needs a degree but because the push to open universities to all means enormous numbers of people have them and other types of education are increasingly difficult to get or unvalued.
And at the bottom? The undeserving poor, the scroungers, the shirkers, people who don't open their curtains before mid-day. Or alternatively those who have been failed by the education system and fallen through the gaps in the safety net. Officially described by terms like 'hard to reach groups', which may reflect the fact that a government that regularly spouts words 'scroungers' perhaps isn't trying that hard to reach them.