Engine knocking when starting up??

Hi i have a 04 TD5 discovery top spec, when it is stating up it knocks and it sounds like something is knocking on the bonnet? Its an auto as well and it struggles to pull of once started it doesnt seem to select gears very quick or very well, any help on This would be a great help, thanks for your time.

have u got someone to turn the key while ur watching under the bonnet??

What's it sound like when
Running?

Yes i can get someone to turn the key whilst i look under the bonnet i will report back on that tomorrow, and it is fine after it has been started up

Check your engine mounts too

I will do thanks