I presume with the SWA being indoors at that point there is no requirement for bottom entry as such, IE it could loop down and top-enter.
Taking it a step further, is there any reason why the top or side of the CU couldn't be drilled and the cable glanded straight into it?
I must admit I'm coming around to the idea of running the SWA through the wall and internally to by the CU, sounds much tidier.