Better I think, I would still look to expand the previous employment section:
-You were there for 18 months, surely you must have at least something worthy of mention, maybe health and safety related, observation skills, training/mentoring new lifeguards or swimmers etc?
-Maybe add your work experience in there, you've worked at Plus4Audio, the Bank of England and Cancer Research UK but it is all hidden away in the text. I think putting them in the with your formal employment would transform the CV from one where people might thing "hmm, this guy doesn't have much practical real world experience, just what he's done at school and the lifeguard stint" to "wow, compared to most school leavers he actually has a fair range of practical exposure".
Essentially what I'm saying is, I would merge some of the employment/experience section such that whenever you actually worked for a organisation outside of school, it goes in the work experience bit to make it clear and obvious to people who are skim-reading dozens if not hundreds of CVs that you have actually had a fair range of practical experience albeit most of it for short periods of work experience.
When I first looked at your (original) CV, it didn't do anything for me, but having looked into the details I think you are probably a far better candidate than the impression it gave off. And strange as it may sound, that's a bad thing

Being a good candidate in itself isn't good enough - you need to make that abundantly clear in the first 20 seconds of someone looking at your CV. Because we spend so much time on our CVs, and are (naturally) self-centred, we don't always realise how little care and attention those who's desk it lands on will give it.