In this talk, I will present an overview of recent formalisations, in the interactive theorem prover Isabelle/HOL, of significant theorems in additive combinatorics, an area of combinatorial number theory. The formalisations of these theorems were the first in any proof assistant to my knowledge. For each of these theorems, I will discuss selected aspects of the formalisation process, focussing on observations on our treatment of certain mathematical arguments when translated into Isabelle/HOL and our overall formalisation experience with Isabelle/HOL for this area of mathematics.