I can't really give an unbiased account of the coffee in this place as it is my favourite coffee shop. Latte is best suited to my tastes, creamy but not cloying; cup full to the top without losing half of the drink to a frothy head. The decaf version has a slight toffee aftertaste.
Sadly, access in this branch in town is difficult due to the nature of the building. There are a couple of wide-spaced steps to the entrance which do not make it easy. The corridor from the front door to the counter is reasonably clear, but the tables and chairs are so closely packed that access with a sholley is awkward and with a wheelchair impossible, unless the table nearest to the door is free. It is, in fact, impossible to be comfortable anywhere due to the furnishings being so densely packed. Manoeuvering the sholley and the tank is only possible if I have a companion. Wheelchair users would be best seated outdoors assuming the weather is conducive and the traffic around the island is calm.
For full access, the branch at the Maybird is best. The furniture is still crammed but there are more options for you if you are hampered by wheels of any sort. This store is used much more by families so on certain days you may find your lunch accompanied by the squall of infants. The heavy usage is taking its toll on the furnishings too, with some of the bigger chairs and cushions looking stained. Staff keep the store clean but overlords of Costa should note that in attempting to conquer the Universe by coffee shop cleanliness is next to Godliness.
Food-wise, the British cheese and ham toasted sandwich is nice enough. Of all the toasties in all of the places I have been, the cheese in this is the most likely to melt into a runny gloop when heated, so beware of puddles on your plate. Or lap. I also prefer the lack of garnish. No sneaked-in green bits. No trying to give it a chic Continental feel by introducing a teensy bit of sundried tomato. And no attempt to bulk it out with an accompanying salad and charging for the privilege.