All of the known mechanisms for magnetically-driven ferroelectricity require a form of magnetic long range order (LRO). Recently however, a new mechanism has been proposed where a fluctuating vector chiral order of spins induces a time-averaged bulk ferroelectric moment in the absence of LRO. From theory it is suspected such a state may exist in a S=1/2 XXZ spin chain, of which our subject material Rb2Cu2Mo3O12 is a promising realisation. Using LET we wish to explore the magnetic excitations of Rb2Cu2Mo3O12, both inside the purported vector chiral state for which T<1.7 K and H<2 T, and at higher field where a dielectric transition occurs at ~2 T and 100 mK to a likely LRO phase. The results of this experiment are needed to clarify the forms of magnetoelectric coupling across the phase diagram of this material, which may include an entirely new form of magnetoelectric coupling.