Why won't my sunroof close all the way or set?

In many case this problem, not uncommon, is related to the retractable wind deflector that pops up when the roof opens and tucks away when it closes. A couple things to check....
First step up on a ladder or the passenger door sill and get a good look at the deflector itself. The mechanism is spring loaded and you should be able to easily push it down into its cubby and it should spring back up when you release it. Inspect closely for blockages by debris.
Second, inspect the track that the roof travels on for missing or loose fasteners (screws). These do come loose and even completely out. In which case the rooitself can get hung up on the protruding screw head or be blocked by a loose screw somewhere in its path.
The last item to inspect is the track and spring mechanism of the deflector for lubricant. There should be visible presence of grease on the tracks as well as the deflector hinge and spring points. If not this also is sufficient to stop the movement of the roof and or trigger the anti trap function. Apply a universal grease or white lithium grease is what I use. The motor of the roof is intentionally not very strong in order to prevent shattering the glass in instances exactly of this nature.
I've never seen any more significant issues with the sunroof operation or mechanics than these. In the event you ate unable to resolve with these tips you can manually close the roof while deciding your course of further action and stop the wind noise. That odds looking tool in your glove compartment is a T-wrench for turning the roof motor and gears for service. Simply remove your overhead light. First the clear lens, then the two screws you will see on either side of the bulb. This will drop your interior light cluster and clearly give you acccess to the center of the primary gear. Insert your wrench (which I believe is a Rover unique design) and gently turn until roof is tightly closed.
I couldn't give you any further advice without a personal inspection, hope this solves your issue. One word of caution, the sunroof glass is easily shattered. Do not apply any force to the glass panel.
Good luck!