I was able to start on £18k and reach £34k within three years, albeit by going back to uni for a year while working (three days work two days uni per week), which was hard work but paid for
That's another difference, isn't it?
My professional qualification was four years while I worked full time, I paid about £5k of it. I went to evening classes.
I later did a degree part time while I worked full time, and that cost me c£12k (just in actual costs, not including travel, books, stationery, unpaid days etc). The classes were on Saturdays. The degree is not specific to my job but it has helped to open doors for me as lots of employers state that you need a degree and I didn't have one.
For the person who said HR 'looks chilled' - it's generally not. There is a lot of responsibility. You don't get "a say in" designing benefits and reward - you have to actually make the decisions, take responsibility, deliver on time and to budget, ensure all the technical stuff behind the scenes works......it's not just sitting around chatting about what would be nice to have. Plus you have to consider a wide range of requirements, not just your own.
You can transition into HR but like all professions, if you move into it, you have to start at the bottom usually. If you have wide line management experience you might be able to move into HR at a slightly higher level in an industry you have experience of but not otherwise.