I am in my first year of my PhD which is not CASE funded. Even though this is the case, is it possible to secure a placement whilst studying for a PhD, some of the people in my lab are going on placements but I think that they were secured before starting. Has anybody secured a placement after already starting their PhD?

you can always try. Read the terms forom your funding body and ask your supervisor. I expect that it will have to be closely related to what you are doining.

I want to do a placement in something unrelated (finance) but have the feeling it will have to come out of my holidays.

If your University has access to Roberts Money you may be able to secure a few months of paid time in an industrial placement either in the UK or abroad. I'm not sure how other Universities work, but my department allows five successful applications a year (possibly more if the budget can manage it), from postgraduates who want to work for a maximum of two months in industry. You just have to prove in the application your time will benefit your studies and also help the department (i.e. set up a collaboration). Hope this helps.

I thought Roberts Money was just for research council studentships. Or are they available to all Phd students?