Not so I'm afraid. Movements outside the published hours are not allowed and HIAL's out of hours indemnity scheme does not cover Barra.
I see in the AIP:
Aircraft movements at Barra prohibited outside AD/ATS hours except in emergency.
It's been some time since I was there, but Paul at Oban said you could land at any public beach subject to the usual rules of the ANO. Maybe there's an exception here.