Epoxy-carbon fibre (CF) laminate composites are mechanically strong but typically suffer from low impact resistance and consequently toughened epoxy resin systems are often used. These systems typically contain high levels of a thermoplastic toughening agent dissolved in the resin, but their increased resin viscosity adversely affects processing. This paper reports an approach to toughening epoxy-CF composites without addition of toughening agents to the resin via use of fabrics coated with an epoxy resin size containing multi-walled carbon nanotubes (MWCNTs). The aim is to concentrate the toughening agent at the matrix-CF interface, where maximum benefit can be obtained. In this study a simple technique is used for coating (MWCNTs) on to the surface of CF fabric for the production of multi-scale CF–epoxy composites. Whilst the main emphasis of the study was on the functional properties of the composites; the addition of MWCNTs to the fibre-matrix interface also improved the Mode I and Mode II ILFT by 105% and 50%, respectively, compared to an equivalent composite reinforced with non-coated CF reinforcement. These increases in ILFT were attributed to two main effects: Firstly, the binder alone (without MWCNTs), which has a much lower glass transition temperature (Tg) than that the matrix (45 vs. 140 °C), hindered crack propagation and increased the ILFT of the epoxy matrix by 25% for mode I and 15% for mode II; Secondly, the energy absorbing mechanisms of MWCNTs during fracture particularly pull-out and fracture. However, in this case the Tg of the matrix epoxy of the multi-scale composites was reduced to 118 °C compared to 140 °C, for the unmodified composite, due to phase mixing with the low Tg size and work continues with higher Tg coatings.