Benefits of a masters postgraduate qualification (UK)

I'm currently studying Computer Science at university as a sandwich course (second and third years of study are separated by a year in industry/full-time work).

I've started to consider a postgraduate qualification, but not in any great detail. I'm currently on placement, which will prove really valuable when it comes to applying for a job and has so far provided me with some great experience of the industry.

Personally, I can't see having a masters qualification as being particularly beneficial to my employment prospects, especially having done a year in industry, but as I said I haven't done much research. And having done an extra year already, I'd rather not extend my degree by a further year.

So would there, in fact, be much benefit in studying further or should I opt for employment straight out of university, whether it be a graduate or otherwise?

Would there be much benefit in studying for a masters later on, after some time in employment, or even studying part-time?

(I've seen similar threads to this, but most, if not all, have been asked by users in the US so I'm seeking any differences for UK or European based education and employment).