Apologies guys, when I wrote DIY I was meaning I had made it myself rather than buying the pnp kit.
I've been busy with work over the past week, working on the radio is a crazy demanding job.
https://www.ebay.co.uk/itm/283302026187
These are the modules I bought, personally I got them from amazon for around £5 for x2, however it looks like eBay has them cheaper (not to sure if the build quality is different)
All you need to do is unhook your battery to save any accidents, remove the gutter trims, take out the two nuts that hold in your outer tail light units and unplug the cable.
For me this is how the cabling worked (UK RHD):
Right hand side light - purple/black cable (2nd from the right)
Left hand side light - black/white cable (2nd from the right)
These two cables needed to be cut in half, with the first half being placed into the entry of the module and the second half (going towards the plug) sticking out of the module exit.
The brown cable for both L+R is the ground wire - this needs a splice crimp so that you can run a second copy of those same wires into the module.
Once that is done you can tweak the timings by using a screw driver on this controller:
The timing controller takes quite a bit of turning to change the delay value.
Before hooking this up to your car I would recommend that you test your wiring on a battery (such as a PP3). Each module has a red LED which lights up to indicate power, and a blue LED to indicate when the delay has finished.
Lastly, I extended the cables of which I had to cut so that I could bag up the modules to make them water tight, before hiding them down in the body panel.