Motivated by a classical question of Mahler (1984), Levesley, Salp, and Velani (2007) showed that the Hausdorff measure of the set of points in the middle-third Cantor set which are ψ-well-approximable by triadic rationals satisfies a zero-full dichotomy. More precisely, the Hausdorff measure of this set is either zero or full according to, respectively, the convergence or divergence of a certain sum which is dependent on ψ.In this article, we prove an analogue of this result, obtaining a zero-full dichotomy for Hausdorff measure, in the setting of more general self-conformal sets with an appropriate adapted notion of approximation. Unlike in the work of Levesley, Salp, and Velani, we show that we are unable to apply the Mass Transference Principle due to Beresnevich and Velani (2006) in our setting. Instead, our proof relies on recasting the problem in the language of symbolic dynamics and appealing to several concepts from thermodynamic formalism, eventually enabling us to use an analogue of the mass distribution principle. In addition to demonstrating how our main result naturally extends the work of Levesley, Salp, and Velani, and complements some recent work of Baker (2018), we apply our main result to obtain a Jarník type statement for the Hausdorff measure of the set of badly approximable numbers which are "well-approximable" in some sense by fixed quadratic irrationals. This relies on the fact that the set of badly approximable numbers with partial quotients bounded above by a fixed M P N forms a self-conformal, but not self-similar, set. Hence this is a novel application of our main result which does not follow directly from previous results in this direction.