This is getting increasingly difficult to use, now you have to fill in a form, have it approved, get a number from Emirates and then drag off to the travel office for the issue of a low priority ticket.
You then turn up at the airport and try to get a flight, the chances of getting on can be very slim. Now, if bumped off, you used to be able to call the Emirates travel centre and get re-listed, then have a shot at another flight.
That situation is no more, according to the latest plan, you have to e-mail Emirates and get another number to allow you to re-list. I have not tried it yet, but I think it will make being bumped from the 08:00 LGW, then resisting by phone onto the 08:05 BHX and then sprinting for the gate a little difficult.
Flydubai's in house travel is easier, all on line with six discounted firm seats per aircraft up for grabs. Can be a little pricey, but they are firm.
Hope this helps with your plans.