Where is the thermostat located? Hijet 1.3

On old vehicles the thermostat was very easy to locate, but on compact modern engines everything seems so crammed in and inaccessible. I own a Hijet 1.3 pickup with limited engine access under the cab seats and a rear flat bed hatch. My problem is poor MPG. I believe the coolant sensor to be okay. I have recently noticed the temperature gauge remains low and doesn't move to its former mid-point position. So I'm assuming a faulty thermostat could be keeping the engine running rich by not triggering the sensor to reduce to idling speed. So where is the thermostat located and accessible from?  Also welcome any related advice. Thanks.

Its basically below the handbrake, not familiar with the pickup but the centre panel is removable in the van, I'd imagine similar with the pickup.
Its a bit of an arse to get at tbh.

What mpg are you getting? Are you sure the temp needle has changed position? My '02 1.3 needle reads about 80% but my '08 stays at around 25% unless in queues or idling when it goes up to 45%, then fan kicks in and goes back down.

Currently 25MPG! I've had my van a while and noticed the temp needle is definitely lower now then before; even on long runs.

Might be worth following one of HJ's guides on checking the lambda sensor serious over fueling will cause a lower rnning temp and bad MPG.

What are the HJ's guides on checking lambda sensor? Can I do this myself or do I need a garage with a computer link? Thanks.