The scratch Australian side - assembled after the original squad had been axed for threatening to go on strike over a pay dispute - took an early lead after capitalising on England's ill-discipline.
But Australia could not cope with the pace of Harlequins' David Strettle, who slid in for two tries - both of which Gollings converted brilliantly from the touchline.
Gollings, the lead points scorer in Sevens history and now playing his rugby for Doncaster, then crossed for England's third.
But head coach Mike Friday will be frustrated at the number of mistakes England made.
They were twice penalised for dissent - back-chat and throwing the ball away - and Australia almost punished Gollings for a careless restart.
England only escaped when Australian Nick Cummins lost the ball forward as he attempted to plough his way over the line.
South Africa booked their spot in the last four with a victory over Samoa.
The rain was torrential and Friday said: "I have been coming to Dubai for 13 years and I have never seen it like this.
"The boys often wonder why we make them bring kit and boots for all types of weather. They now know."
England, based at an academy out in the desert, have been following the Ashes action closely.
Friday added: "It's great to see England beating the Aussies in any sport and it's great to see the boys down under play so well. We are obviously keeping in touch with it. That was some innings from Collingwood."
Wales qualified for the final of the Shield - the bottom tier competition - after a 19-12 extra-time victory over Scotland.
The two sides met after being knocked out of the Bowl competition in their opening games of the day.
Scotland were beaten 33-12 by Portugal and Wales, who pulled off one of the major surprises yesterday in beating Samoa, fell 24-10 to Argentina.
Wales took an early lead through Llanelli's Jonathan Edwards but Scotland adapted better to the conditions and, helped by superior handling, moved ahead with tries from Ruaridh Jackson and Murray Bringhurst.
But Wales pegged them back just before full-time. Edwards scored a brilliant second try after Rhodri McAtee's storming run from half-way.
McAtee missed his conversion from right in front of the posts - but Cardiff's Tom James beat three defenders to score the try that carried Wales through in sudden-death extra time.
Wales face the Arabian Gulf for the Dubai Sheild.