looking for UK TV ad from early 90's

does this jog any memories?
send-up of Aliens - a space marine, called Brad, is cautiously stalking through a spaceship on the lookout for an alien. our POV is split between watching Brad, and then a 1st-person of some alien zooming through these tunnels towards him.
every so often, some chap over an intercom asks him if he "can see it yet?" "Nope."
alien suddenly bears down on him from above. he looks up, drops his weapon, and runs off set shouting "SHHHUUUUURRREEE!"
cut to outside of ship, then display of advertised product (unsure what this is, but im thinking Kit Kat, Weetabix, Beer, etc. etc.)
ive been searching for this one for months, can anyone help me?