What switchboard would fit a space of 450h x 220w

[JR1210]

I am installing a 14KW ducted aircon unit in a single phase house, which requires a 40A breaker. I was thinking of asking the electrician to put in a consumer unit / switchboard while installing the circuit breaker. There is only 450 height x 220 width available in the box. Is it worth while doing this and would a unit fit that size, either 2 rows or put the unit sideways? Picture of current setup below

Electricity board