Someone else who went to school in Edinburgh
anyway...
Do check your formatting - the top two bullet points in your "Relevant Experience" section are way bigger than any of the others, for example. It's a small thing but if you get it wrong it just looks like you don't care enough to bother. You could also try laying things out in tables to get rid of the unsightly '/'s in your work experience and to make it a bit easier to read. Everything seems really spaced out so you may find that with tables you are able to put things closer together and can get the CV down to a full page - otherwise you really need some extra stuff to say (e.g. expanding on your work experience some how) as your second page looks a bit empty!
I'm really interested to know why you've split things into "Relevant" and "Other" - there doesn't really seem to be a common thread! If there is genuinely some logic then fair enough but otherwise I would definitely combine them as they all look potentially equally relevant to a job. I would be careful with how much detail you give in the bullet points - for example, the names of the productions you were involved with don't really need to be stated (unless perhaps you're going for a job as an actor? but even then...) but with your volunteer role I'm not really sure what you mean by "leaflet pouch around street-poster" so perhaps some more explanation is required there if you want to include it. Make sure you phrase things well too, for example "Assist Weekend Docent with visitors by beginning and ending tours and handing out flyers." sounds a bit better and is also in the present tense, as it should be if you're still doing it. "Weekend volunteer" is your job title so doesn't need re-stating.
Unless your hobbies and interests are actually really relevant to the job you're applying for, I'd summarise it down, e.g.:
• Active member of KCL Muay Thai Kickboxing society and also like long-distance running, rowing and sailing.
• Enjoy the performing arts with 8 years choir and choral experience, ability to play piano and bagpipes and experience as an actor and technical crew member in various drama productions.
• Held rank of WO2 in CCF at school. (Note: outside the CCF and maybe armed forces, it's really unlikely anyone will know what a "WO2" is - I certainly don't! You'll need to explain it, and may want to expand "CCF" too.)
• Hold a Gold Duke of Edinburgh Award.
Hope some of that helps!