Climate change mitigation plans and recent tension over gas supply generate significant incentives for reducing reliance on fossil fuels in the built-environment, with an increase in installing renewables and in electrifying the heating sector. However, the seasonal imbalance of energy supply and demand is expected to increase further. Sector coupling enabled through power-to-hydrogen-to-power (P2H2P) systems that include seasonal storage can partially mitigate this issue. In this work, a hydrogen-based multi-energy system is modelled with a mixed-integer linear programming based Ehub optimization tool. While results show that the P2H2P system is technically and spatially feasible and more flexible, its large hydrogen storage is associated with high costs and embodied carbon emissions. Finally, an outlook for P2H2P systems for integration into renewable-based systems is presented.