No, This Mortal Coil is not a goth band, because they play Dream Pop/Neoclassical Darkwave/Ambient, while goth music consists of Gothic Rock and its derived genres, like Deathrock, Darkwave, Ethereal Wave, and Coldwave.

However, they do have a significant goth influence and even have some goth songs in their repertoire, like "The Last Ray" and "Sixteen Days / Gathering Dust".

It is important to note that while this band is not goth, its members did make goth music as part of acts like Breathless, Cocteau Twins, and Dead Can Dance.

If you want to dive into the goth music scene, some of the bands that might appeal to you if you enjoy This Mortal Coil are Collection d'Arnell-Andrea and Love Spirals Downwards.