It's hard to imagine where it could possibly be originating from as the VX's oil sensor is an eletronic unit, so there's no plumbing into the cockpit from the oil galleries. The only thing coming through the firewall that transports any liquid is the lines for the heater core and evaporator.
Do you have an after-market oil pressure gauge installed? If so, check the line as it's not uncommon for them to crack and leak. If not then check the firewall on the engine side with a good bright light to see if oil is perhaps being sprayed against the firewall near one of the rubber wiring grommets. If this is the case, hot oil can accumulate enough around the grommet to be wicked inside by the carpet underlayment. Then you'd need to address the source of the oil.
As for servicing the VX in the UK hopefully some of the other owners there can chime in an voice their experiences and recommendations. Failing that, find a shop well versed in Troopers as most of the driveline is the same. Especially since y'all have the short-wheelbase Troopers there.