I've recently had a number of requests for advice on processing SARs recently. I'm happy to advise but there is good guidance you can share with colleagues on the ICO's website:
https://ico.org.uk/for-organisations/guide-to-data-protection/principle-6-rights/subject-access-request/
If you aren't comfortable with such requests, now is the time to ensure you know what to do as the timescale will be reduced when GDPR comes in on 25th Mat 2018.