I assumed you were about average fitness and strength for your size and that when you mentioned trips around the islands, you were thinking about carrying gear for a couple of days rather than a couple of weeks.

Another assumption that is much harder to quantify is the amount of stability with which you would feel comfortable. Stability is important, but is quite complex. Some kayaks feel quite stable sitting level but don't get much better as they lean over a bit. They tend to be the ones with flat bottoms and hard chines. Others feel a bit nervous sitting level but get much more stable as they lean a bit. They tend to be the ones with round hulls and quite a bit of flare on the sides.

That is a bit over simplified and what makes it even more complicated is that it is quite easy to make a kayak that is 52cm wide more stable than one which is 54cm wide. Fuller bow and stern tend to add stability.

Something like the Redfish "Silver" or the Guillemot S would be close to what I had in mind.

http://www.guillemot-kayaks.com/guillemot/node/40/draw

http://www.redfishkayak.com/silver.htm