MAX gross weight can be found on the VIN plate, usually under the bonnet. The MGW is shown in KG's and usually the number below the Chassis Number.
So for eg;
MGW - 2000
Un-laden weight - 1400
This means, The vehicle, as it was built weighs in at 1400. Which means you can add 600 in water, tools, body weight, roof rack, ladders etc.
The MGW is the final weight, there is no le-way in it. If you are taken to the weigh bridge and it comes in at 2010 then you can be 'done'
However, not sure if the un-laden weight includes an allowance for a full tank of diesel?