Pre-hearing judgement / pursuit of arrears

Rent Arrears

With mounting arrears, a so called absconded tenant despite , rest of the family inhabiting our property, what actions can already be brought to trace the AWOL tenant ahead of any hearing judgements and working on the case of recovery ? (currently 3rd week of November for a `review hearing`)..... The arrears are already sizeable （xxK GBP)and the longer it goes with no tracing being initiated, the harder it will become to get something from the tenant assuming they are sitting on assets somewhere ?
Legal ( under our current insurance) is saying the debt needs to be quantified and a possession order issued first before they get going.....