There aren't many choices.
The two most common.
- Get given the money - often from parents remortgaging their home and sometimes from inheriting it.
- Work and save as much as possible. It is more than possible to save £15k per year if you choose the right options, work hard and save. There's your £70k in five years.
There are other options. You could mortgage your own home if you own one outright or marry into money or many other ways. But the above two are the most common.
You can also work and study at the same time. Though I think that path is a lot harder.
rudestuff above is very right. Most people don't have the discipline to follow through with working hard and saving money. It's not an easy road, but it shows grit/ determination and will develop work and life skills.