I made a booking within 24 hour's of Gibraltar being announced. I'm taking my 81yo mother on a day trip. As you mentioned, it's simply too good to resist.
I noticed on the Southampton Airport network map on the link provided that Alicante is included. On further investigation it appears that BACF have added now Alicante which is scheduled to start on the 26 June 2021.
Looking past the summer schedule I wonder if BACF will announce any winter destination's from Southampton Airport such as Chambery.
With regards to Eastern basing their EMB-190 at Southampton Airport for summer 2021, I'm surprised that they have not announced any further destination's to the previously announced Gibraltar. With Gibraltar operating twice a week on a Mondays and Friday what will the aircraft be doing on the remaining five days.