Driver advice please

Hi all, looking for some guidance, I am attempting a build project and need some help please. I have a Li-on battery pack 11.1v, 4400mAh, a driver rated @ 4-18v, a led on a board, an old HID light head. As this is my first project and I have limited electrical knowledge but good practical skills(can fabricate and solder etc.). I plan to use an interference fit alloy rod 35mm x 30mm as a heat sink, my question is do I need to fit the driver to the heatsink and if so how? The heatsink has all the circuitry on the top side but the wiring connections from the switch connect to the rings on the underside meaning I cannot just mount it to the heat sink using conductive cement.
Any advice appreciated.

https://www.dropbox.com/s/60cfi4kh4ep78xl/103_1096.JPG?dl=0
https://www.dropbox.com/s/w8a9m3ojmp30b28/103_1097.JPG?dl=0
https://www.dropbox.com/s/02kh8fsynqhh8wb/103_1098.JPG?dl=0
https://www.dropbox.com/s/205tgpzzk5rpc07/103_1099.JPG?dl=0
https://www.dropbox.com/s/pgdyjr4ev48a46u/103_1100.JPG?dl=0

Depending on the rated current of the driver, you may or may not need heatsinking on it.

That driver is designed to mount in a recess on the backside of the pill, which in your case has morphed into a much larger heatsink, with the electronics on the inside and the battery up against the center pad on the flat (outside) side. The only heatsinking it would normally get is from the the edge of the circuit board being pressed against the supporting edge of the pill/heatsink. That can in fact provide a small amount of heatsinking for the electronics, but even that may not be necessary.

it looks like OMS 10W HID light Phantom .

You don't need such clumsy heatsink , special with those Cree XML . I would made H shape heatsink on one side driver on other side driver , cca 8mm thick wall between led and driver and small fins of 5 mm from side to have good thermal exchange with core .

Of course , battery side of driver should be insulated - just simple pop it on dual side thermal tape to fix it .

Thanks guys, yes it is an OMS Phantom, I have had it laying around for a couple of years now, the switch circuit was faulty I have now fixed that(I think) so time to get the light side sorted. The led and driver I have laying around. The driver puts out 5amps. If I do not need such a heavy heat sink (8mm instead of 30 mm) I may try attaching the driver to the heat sink with thick(5 mm) insulating heat sink pad attached around the soldered wires.

how much place you have for reflector you would use ?

Not decided on reflector yet, have ordered an assortment from DX to test.