I have actually managed to do this by lifting some of the code on the downward arrow icon for the shopping basket and applied some custom CSS.

.sf-mega-menu .menu-item-text{
    padding-right:16px;
    position:relative;
}
.sf-mega-menu .menu-item-text:after{
    content: "\e60d";
    font-family: 'atelier';
    position: absolute;
    top:22%;
    right: 0px;
    height: 15px;
    line-height: 15px;
    font-size: 12px;
}

It might not be the best way but open to suggestions if anyone can improve it.

Many thanks!