Managed to wipe out the base eventually but must have killed the scientist, the 6 live captures I got r coming up as 2 mercenary soldiers of three different rows in the alien containment, recovered an HWP data disk, I assume there will be further opportunities to get to laser weapons as I've just started my 1st terror site vs Sectoids/Cyberdiscs.
Did you get the Armory building (the one with all the Omega weapons laying around)? If you have recovered all the types of weapons present on that building and research them (you need only to assign 1 scientist) you can unlock the Omega Weapons topic, which allows you to manufacture Omega weapons & clips.
The Improved HWPs should also be a great help: they have the armor and TU/Stamina of Hovertanks, plus the Tank Cannon gets upgraded to an autocannon.
There is another opportunity to develop Laser Weapons:
But yeah, until you get another opportunity, you're stuck to conventional weapons until you get the chance to research plasma weapons. However, you can get Power Suits easy if you capture and interrogate a specific alien rank, which can be a great help to survive.