Hi there
Been told to couple up to a trailer tomorrow for the first time since my passing my C+E test. The trailer is going to be fully loaded with bricks so was just concerned as to what precautions I need to make differently as opposed to coupling up to an empty trailer? Thanks 
Resistance when first backing under… Just take your time, get out have a look… If you need to drop the air on back of the unit do so, if the trailer has been left too high then raise the unit so you don’t miss the pin and trash back of the unit 
You’ll be fine…
As above, it will take a bit more " “oomph” to get the unit to slide to the pin just don’t overcook it.
Oh, and it might feel a bit heavier than the test trailer on the road, lol.
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If you’re unlucky the trailer height will be beyond the reach of your unit, raised or lowered to the max. If that happens then you’ll have to wind the trailer up/down to get it to a level the pin can reach the fifth wheel safely. Remember there are two positions on the winding handle; pull it out for normal winding, but push it in for a low gear wind - that’s useful if the load is so heavy that the legs won’t move. You’ll have to wind a whole lot more, but you’ll be able to get past the resistance of the legs under the load.
Back up to the trailer then before you go under drop the air out of the unit. Continue under till you see the trailer go over the drive axle mudguard, you can get out and check the turntable is under the trailer. Stop, park brake on and then raise the suspension. You’ll see the nose of the trailer begin to rise. Once its up high enough, continue to reverse back. You will not miss the pin and if you’ve raised the nose up high enough the legs will be off the floor by a inch or two. By doing this you’ll not scrap the legs across the deck if you aren’t completely square with the trailer as the pin will find the edge of the jaws then it will follow the jaw line into the hole.
By doing this you’ll look like a pro because you’re going to get a nice soft “click” compared to a loud bang and you’re taking care of company gear so your boss will be happy too.
Radar19:
Back up to the trailer then before you go under drop the air out of the unit. Continue under till you see the trailer go over the drive axle mudguard, you can get out and check the turntable is under the trailer. Stop, park brake on and then raise the suspension. You’ll see the nose of the trailer begin to rise. Once its up high enough, continue to reverse back. You will not miss the pin and if you’ve raised the nose up high enough the legs will be off the floor by a inch or two. By doing this you’ll not scrap the legs across the deck if you aren’t completely square with the trailer as the pin will find the edge of the jaws then it will follow the jaw line into the hole.By doing this you’ll look like a pro because you’re going to get a nice soft “click” compared to a loud bang and you’re taking care of company gear so your boss will be happy too.
THIS ^^^^ 
And remember anti clockwise to wind up and clockwise to wind em down
Back up to the trailer then before you go under drop the air out of the unit. Continue under till you see the trailer go over the drive axle mudguard, you can get out and check the turntable is under the trailer. Stop, park brake on and then raise the suspension. You’ll see the nose of the trailer begin to rise. Once its up high enough, continue to reverse back. You will not miss the pin and if you’ve raised the nose up high enough the legs will be off the floor by a inch or two. By doing this you’ll not scrap the legs across the deck if you aren’t completely square with the trailer as the pin will find the edge of the jaws then it will follow the jaw line into the hole.
By doing this you’ll look like a pro because you’re going to get a nice soft “click” compared to a loud bang and you’re taking care of company gear so your boss will be happy too.
This is how we teach and it’s disappointing that it’s not the norm.
btw, you (OP) have been trained on a partially loaded trailer - so you’re part way there. All the best, Pete 
Also, remember the BLACK protocol (and double check it once you think you’re done!!!) and to take the keys with you when you get out of the unit, in case it is one of those one’s that likes to lock itself automatically!
EDIT: And if you get interrupted by anything. Restart!!!
Thanks everyone for the solid advice, took my time but coupled up no problem. Lifting the trailer up with the unit definitely helped!