I will be going on a cruise around the med, towards the end of july and was wondering if this counts as a Annual multi-trip travel or a Single trip...and so which insurance should I apply for.

This is a single trip, if you go onto one of these confused.com sites, they will show you best offer at the moment. Also check if your bank has free travel insurance attatched to your bank account as most do now days. Have a great holiday and don't forget your travel sickness pills, you will need them.

Single trip but check with your insurer to make sure they are covering this as a single trip.