The 1D ferromagnetic coupling within the chains of Tb(HCO2)3 appears to play a key role in its greater magnetic cooling performance above 4 K, compared to Gd(HCO2)3. Furthermore below 1.6 K the packing of these ferromagnetic chains into a frustrated antiferromagnetic triangular lattice appears to enable the emergence of long range 1D magnetic order with only short range antiferromagnetic correlations between its chains; a state resembling a triangular Ising antiferromagnet. The effect of applied magnetic fields on the combination of low dimensional and frustrated magnetism in Tb(HCO2)3 is unknown and we aim to probe this in both its ordered and paramagnetic states using the WISH diffractometer, taking advantage of this instruments high resolution and intrinsically low background to accurately measure changes in its magnetic scattering at fields up to 5 T and between 1.5 and 20 K.