it depends can either go in to a spare way in db 50 amp max mcb or a separate 60 to 80 amp switchfuse connected on mains tails from meter with double pole Henley mains service connector blocks
I did mine with 10 mill 3 core armour
From consumer board in garage one 28 metre length
Had a hell of a job getting the wires in to a 13 amp plug
I clipped and buried the cable a mate did the fancy gland nut terminations
I still have a 18 metre length of cable doing nothing if any one needs it .
A decent bottle of wine and a forum donation would secure it .