Fitting a new harness and new rocker cover gasket to my 01 TD5 over the weekend. It looks straight forward enough, but thought i should double check with the oracle if anyone has any tips on this process. Any extra sealant on cover etc???

You can use a drop of Hylomar Blue, especially at the rear of the engine where they always appear to leak.

It is always a good idea to use a Genuine Part gasket as the aftermarket ones can sometime be badly made and don't fit well. Also store the gasket flat before fitting so it fits better.