I have over 35 years in the electrical trade in the USA . But no experience over seas .
My 2012 Leaf has 3.3 kw charger . ( The charger is built into the car . )
An EVSE is not actually a charger . It us an input cord and an output cord with a " box " in between " .
The box contains some electronics that communicate with the electronics in the car . It also contains a device that turns off or on , stopping or starting the flow of electricity going to the car . In larger Level 2 units , it is a contactor .
My Leaf came with a 120 VAC Level 1 " trickle charger " .
Our older house , built in the 1950's , all the original 120 VAC receptacles are 2 prong wired with 2 wire Romex cable . No earth ground .
My factory EVSE would not work on a receptacle without an earth ground .
I had intended to install a Level 2 240 VAC single phase EVSE . I ran 40 amp Romex cable to a 40 amp 2 pole circuit breaker and installed a NEMA 6-50 R receptacle ( straight blade 50 amp ) . ( Your NEMA 6-30 R receptacle is 30 amp 240 VAC with the 3rd blade being earth ground . )
My EVSE is a GE WattStation & I paid $ 399 + about $ 36 freight , USD . This is over kill for my Leaf with 3.3 kw charger . But should be fine if I trade it in , in the future , for an EV with a " larger " charger . Also , it was about the same price as lower amperage units .
3300 watts / 240 VAC = 13.75 amps
Multiply by 1.25% since this application would fall into the category of continuous duty . 13.75 amps x 1.25% = 17.1875 amps . Since the charger is not 100% efficient , throw in another amp or two & it should be OK on 20 amp wire ( # 12 copper wire , American Wire Gauge ) .
You said your Leaf has the 6.6 kw charger . My EVSE would be OK for your 6.6 kw Leaf . Yours would be OK for my 40 amp wire and 40 amp 2 pole circuit breaker . Should I , one day , buy a newer Leaf .
Now , back to your situation . The EVSE electronics and / or software can communicate with the Leaf , to set it to pull less than the maximum 240 VAC load / current . If you have 25 amp wire and circuit breaker , I suspect your EVSE is set for 20 amps 240 VAC , max .
My Level 2 EVSE has internal jumpers that can be changed to tell the unit to use less than the 32 amp 240 VAC max .
I hope you have all the details worked out & it all works OK , on first try . Please keep us updated .
God bless
Wyr