You will arrive at LGW c. 0100 at best. I woukd be tempted to (a) grind through the experience, and (b) try to get better flights next time [only joking, I know it isn’t easy].
Sadly the Lounges will be closed, and Airside at LGW isn’t exactly charming. But staying Airside may be the best if a bad job.
Do enjoy Malta ... I hope you’re traveling ‘in season’! It’s a bold journey for you guys, but easy[ish] for us, apart from the awful flight schedules from LGW!! My MLA TRs are linked below this post.