(This is from the perspective of a young person who doesn't have a family to look after.)
Housing/commuting: the cost of this can vary enormously even over relatively small distances. Most cities have "nice" (expensive) areas and "poor" (cheaper) areas, where in practice you're just paying a premium for nicer architecture and a higher proportion of white people. It's therefore very often possible to live within walking or cycling distance of the centre without paying through the nose for it. Many places are perfectly fine to live without owning a car, though a lot of car addicts will tell you otherwise. Commuting by rail is rarely worth it, as the trains are less reliable in occasional bad weather, and ticket prices routinely go up above inflation. London is probably the only place where it makes financial sense to commit to commuting by train, although these trains will normally be totally packed.
Transport: We have some of the most expensive train tickets in Europe, but it still makes sense to use them for longer journeys if it means you don't have to own a car. For ~£30 a year you can buy a railcard, which gets you a 33% discount on all tickets (down to a minimum of £10 on tickets for travel before 10AM), this is very likely to more than pay for itself if you travel a few times a year. Tickets can also be gotten considerably cheaper by buying in advance, getting two singles instead of a return, or even four or more singles for longer journeys, because the triangle inequality frequently doesn't apply. There are also a lot of coaches and buses, but nowadays these are rarely better choices than trains or cycling/walking.
Investing: You can contribute somewhere around ~£10,000/year (and it's going up) into an ISA (Individual Savings Account), which can either hold cash or stocks/shares/ETFs/&c. This is totally tax free except for a 10% of dividends. You can invest up to 100% of your income in a SIPP (Self-Invested Personal Plan) which is similarly tax-advantaged but there is no legal way of accessing it before you are 55. Therefore your ISA should take priority. Some public sector jobs (like teaching) come with quite generous pension schemes. Our Lending Club equivalent is called Funding Circle, and only lends to businesses; currently, loan defaults can't be deducted from returns for tax purposes, but this might change in the near future.
Real Estate: The 1% and 50%/2% rules are rarely, if ever, going to apply in the UK. However, expenses for a landlord are lower because the UK doesn't have true property taxes; Council Tax is paid by the tenant, not the landlord, and is determined by which Council Tax band the property is in, rather than the value of the property directly.
Groceries: Normally it's best to split your grocery shopping between a family-run supermarket and a chain supermarket; most basics can be found cheaper at some family-run supermarket, but a few things aren't available there, or are more expensive than at a chain supermarket.
Health Insurance: For most people, this is not an issue at all. We have universal healthcare, free at the point of use, paid for by general taxation. Most of us are very happy about this. Private health services are available, but unnecessary except for occasional one-offs.