Sinkholes pose significant risks to infrastructure and safety, emphasizing the need for early detection methods as their occurrence rises due to climate change. The ongoing SINEW project aims to provide early warning of sinkhole expansion using combined fibre optic sensing and radar satellite imaging to protect critical linear infrastructure. This paper presents key findings from experimental and numerical campaigns validating the use of distributed fibre optic sensing (DFOS) for early subsidence detection. 1g laboratory experiments demonstrate distinct signature strain profiles during sinkhole formation, with finite element analyses providing insight into soil-cable behaviour. Numerical scaling confirms the technique's feasibility under realistic stress levels and 3D sinkhole conditions. DFOS proves capable of detecting active sinkholes at an early stage, even when cables are situated away from the subsidence centreline, albeit a weak signal that requires complementary monitoring investigations. In this instance when uncertainty arises regarding potential cavity formation in a specific area, combined Multi-Temporal Interferometric Synthetic Aperture Radar (MT-InSAR) serves as an effective complement to pinpoint the location of the subsidence. Analysis of a car park collapse demonstrates MT-InSAR potential, detecting settlement profiles of a few millimetres years before collapse, and promising significant advancements in remote sensing technology.