Overvoltage and Surge Protection for a house in Malta with 3 phase 63A supply

Thanks all for your comments. I am not an expert in these matters, so please bear with me whilst I try to outline the issues:

1. Malta is largely TT (Mike): The electrical system in my house is indeed TT (In Earthed Neutral (TT) System, the neutral from the main transformer is connected to the ground though an earth ground and all metallic parts of the equipment and loads are connected to another earth ground). An earth rod was installed and tested in 2024, but it is close to distribution board DB-X inside the house rather than close to DB-A which is located in a IP65 box in my front garden. This IP65 box also contains the main meter which is connected to the EneMalta cable that runs down the facade.
2. Considerations about the earthing arrangements (Andy): The cable from DB-A to DB-X does contain a Circuit Protective Conductor (CPC) as well as neutral, L1, L2, L3 wires - 5 wires total contained in a non-armoured PVC jacket which complies with local standards. Andy makes a good point about it being unwise to use this CPC wire to provide a conduction path from the Surge Protection Device (SPD) to the earth rod near DB-X as I want the energy from any potential lightening strike to stay outside my house. Therefore I am considering adding a further earth rod in the front garden near to DB-A which would be used only by the SPD. Would this address the issue?
3. Type of SPD - CT1 vs CT2 (Andy): I will specify a CT2 SPD.
4. MCB vs RCD (Andy, Chris): My understanding is that MCBs protect the cable whereas RCDs protect people against electric shock. You can see from the diagram of DB-X that I have employed RCBOs (combine MCB and RCD in one unit) for all the power and lighting circuits in my home fed from the DB-A incomer, so I only need MCBs in DB-A to protect the cables from damage from excess current. The faster tripping time of RDC is irrelevant as a MCB will trip well before the cable is damaged.  
5. Circuit Breaker arrangements (Andy, Chris): The diagram for DB-A shows a MCB protecting the cables downstream from the meter. It also provides a convenient way to isolate the supply to my house. In addition there is a MCB in DB-X connected to the incomer from DB-A which protects the downstream wiring as well as providing a convenient way to isolate the supply from inside my house. Chris seems to suggest that the MCB after the contactor in DB-A is redundant as I had suspected. However, it wouldn't harm to include this MCB as belt and braces as suggested by Andy.
6. Protection of SPD (Simon). The SPD is protected by an upstream MCB so if the SPD goes short circuit then this MCB will trip. There is also a further MCB in the meter box provided by the electricity supplier, EneMalta. 

In summary, I need to fit a further earth rod in my front garden to provide a conduction path from the SPD and then fit the devices shown for DB-A with the SPD specified as type CT2. Clearly, this work will be done by a registered electrician not me.

Again, thank you all for the comments. They are much appreciated. Any further suggestions grateful received.

Thanks all for your comments. I am not an expert in these matters, so please bear with me whilst I try to outline the issues:

1. Malta is largely TT (Mike): The electrical system in my house is indeed TT (In Earthed Neutral (TT) System, the neutral from the main transformer is connected to the ground though an earth ground and all metallic parts of the equipment and loads are connected to another earth ground). An earth rod was installed and tested in 2024, but it is close to distribution board DB-X inside the house rather than close to DB-A which is located in a IP65 box in my front garden. This IP65 box also contains the main meter which is connected to the EneMalta cable that runs down the facade.
2. Considerations about the earthing arrangements (Andy): The cable from DB-A to DB-X does contain a Circuit Protective Conductor (CPC) as well as neutral, L1, L2, L3 wires - 5 wires total contained in a non-armoured PVC jacket which complies with local standards. Andy makes a good point about it being unwise to use this CPC wire to provide a conduction path from the Surge Protection Device (SPD) to the earth rod near DB-X as I want the energy from any potential lightening strike to stay outside my house. Therefore I am considering adding a further earth rod in the front garden near to DB-A which would be used only by the SPD. Would this address the issue?
3. Type of SPD - CT1 vs CT2 (Andy): I will specify a CT2 SPD.
4. MCB vs RCD (Andy, Chris): My understanding is that MCBs protect the cable whereas RCDs protect people against electric shock. You can see from the diagram of DB-X that I have employed RCBOs (combine MCB and RCD in one unit) for all the power and lighting circuits in my home fed from the DB-A incomer, so I only need MCBs in DB-A to protect the cables from damage from excess current. The faster tripping time of RDC is irrelevant as a MCB will trip well before the cable is damaged.  
5. Circuit Breaker arrangements (Andy, Chris): The diagram for DB-A shows a MCB protecting the cables downstream from the meter. It also provides a convenient way to isolate the supply to my house. In addition there is a MCB in DB-X connected to the incomer from DB-A which protects the downstream wiring as well as providing a convenient way to isolate the supply from inside my house. Chris seems to suggest that the MCB after the contactor in DB-A is redundant as I had suspected. However, it wouldn't harm to include this MCB as belt and braces as suggested by Andy.
6. Protection of SPD (Simon). The SPD is protected by an upstream MCB so if the SPD goes short circuit then this MCB will trip. There is also a further MCB in the meter box provided by the electricity supplier, EneMalta. 

In summary, I need to fit a further earth rod in my front garden to provide a conduction path from the SPD and then fit the devices shown for DB-A with the SPD specified as type CT2. Clearly, this work will be done by a registered electrician not me.

Again, thank you all for the comments. They are much appreciated. Any further suggestions grateful received.