Wow, that was... interesting!
We had one third of a game, as it was taking us so long to get through the rules and figure everything out that it had got dark by the end of my opponents second turn!
I'm pleased to report that the Mandrakes won their first and only combat against an XV88, causing one wound and receiving none in return. However, I didn't realise that this meant he needed to take a morale check, and they all stayed locked in combat. The mandrakes passed all tests they were required to make throughout the next phases but sadly failed to take that last wound off the XV. They will return though!
We're going in to store on Saturday so we can get some help from people that actually know what they're doing, in the mean time here's what I remember of my opponents list, I don't think it was legal (I let him have Farsight, though he didn't get used anyway).
Farsight - reserved, didn't get used
3x XV8's with a mix of flamers, plasma weapons and a burts cannon (I think)
12x Fire wariors with 6 rifles and 6 plasma carbines, and plasms grenades mounted in a devilfish (burst cannon and
TL missile pods)
2x XV88's with rail guns and plasma guns of some variety
2 squads of 3 stealth suits with shield drones.
Squad of kroot - reserved, didn't get used
8 fast attack drones - reserved, didn't get used
Some amusing things that happened:
I get turn one, only move my jetfighter 6", drop 2 missiles on top of a stealth suit squad, but only work out the wounds for one missile
He shoots an XV88 at my archon and his incubi retinue which is 6" away from the firing XV88. He rolls to scatter, and finds it right back on top of his head!

Saves were made though :(
His remaining stealth suits immobilises my jetfighter with its first and only shot
So yeah, a reet amateurish and bloody clueless game!
Question:
Can XV88's fire both shoulder and arm weapons in the same turn?
I have a feeling that he was getting to shoot a lot more than he actually should have been! His XV8's had those sensors that let him shoot both guns, though I dont think the 88's did...?