Hi Ash, manic day so sorry for delayed reply.
Basically you need to import the images into a 'Pro' version of Adobe Acrobat (one of the components of the creative suite) to then create the PDF. CS3 is a little out of date (we've had cs4, cs5, cs6, cc and cc2014 since then) but should still be fit for purpose.
Once you have it as a PDF, stick it up on dropbox and I can optimise it for you with cc2014 (creative cloud 2014 version). Hope that makes sense. J.
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