How do I install my new cooker?

I have just purchased a new electric Smeg suk91cmx5 cooker. It says that it has nominal power output of 13.4kw and requires 45 amp power supply. My existing consumer unit has 10mm cable running in to a 40a type b breaker. I will be using a 45amp cooker switch but I am confused as my consumer unit's highest breaker is 40a and I have checked with the manufacturer, Proteus and this is the highest rated mcb.
Will the 40 a type b breaker suffice for the size of cooker as it will be running on 10mm cable? or do I have a problem?