Your questions and answers
Q. I read on another website that when applying to universities your statement is supposed to comprise 50% about the course and how you are suitable, and 50% talking about your hobbies on work experience. What do you think?
I'm always suspicious when I see statistics like this, and I do suspect that people just pluck figures from the top of their head. There are no grounds for splitting up content like this, and especially since the reader won't be dividing things up. For the most part, the reader will mainly be just assessing whether or not you are (A) really interested in the course, and (B) up to the academic side of things.
There are other considerations that are possible factors. For example, there are league tables related to universities are a consideration even when writing statements. However, the main things to consider are A and B above. You need to address what the course leaders are looking for, and do it well.
Significantly, the figures quoted don't even make sense.
You mention the site recommends talking 50% about the course and how you are suited to it, but don't mention how they think the split should work.
For example, is it 40%-10%?
It is unclear.
Also it doesn't even tally with commonly recognised UCAS application advice regarding avoiding making your statement too course specific. Significantly, this tactic may backfire if you are applying for multiple courses that vary to some degree.
Also, it's quite nonsensical to say spend 50% of your statement on ‘work experience’ as many students do not have work experience - let alone relevant work experience.
Yes, you could spend half your statement talking about hobbies and part-time jobs, but if most students did this then half the statement would be about things like working in shops, garden centres, newsagents etc. It's not really the kind of thing that most course leaders want to hear, or are interested in. And in your case if you are applying for a history degree, it's not really going to add much value.
You are better off just forgetting about arbitrary figures that certain Webmasters arguably just make up off the top of their head, and instead playing to your strengths. For this you need an open mind and a flexible approach. In your case this means not going to excessive detail about your nursing assistant work, and instead concentrating more on things that the course leaders will be interested in such as things that are relevant to A and B above.
At the same time, it's really up to you, and if you want to spend another 45% mentioning non-relevant work experience and hobbies then this is your prerogative.
However, it isn't really advisable if you want to make an impact on the course leaders.