You can calculate what current is going through the charger when charging your vehicle by looking at the CT clamp reading and deducting what your house is using.
For example your current CT clamp reading is 9A, if the charger was pulling the maximum 32A the CT clamp reading would read 41A (41 – 9 = 32A)
To convert 32A for example into kW – Current I in Amps (A) x Voltage V in volts (V) / 1000 = Power P in Kilowatts (kW) ( I(a) x V(v) / 1000 = P(kW)
32 x 230 /1000 = 7.36kW or 7.4kW rounded.
You need to take into account any voltage drop due to the cable run supplying the charger, which may result in a lower kW overall.
The nominal voltage in the UK is 230V with a tollerance of +10% and -6%. Unless you know your exact voltage coming into your home use 23ov in the calculation and add 10% and -6% from the calculation to get best and worse case if you wish.
Take into account loss in the type 2 cable and a conversion factor of the cars onboard charger converting AC to DC voltage, which by rule of thumb can reduce the actual charge going into the car by 10-15% less than what is at the charger itself.