Grey t&e is never suitable for external use, even buried.
It can be degraded by UV light if exposed to the sun, and rodents love to chew it.
As mentioned, armoured cable would give sufficient protection.
I would spur it, then go through a double pole fused switch, so the outside part can be easily isolated in the even of a fault.
Ideally, the cable should come from its own circuit direct from the CU