You may want to go back and read post #'s 267-270 (click link below).
I'd try the aftermarket Lubelocker gasket linked in #270:
LR4 Transmission Fluid Change: Pan Swap Option
It will be impossible to use anything but the side port to fill the transmission. Filling from the bottom will just have the fluid dropping right back onto your face. Ryan is correct. Unless there is a plastic pipe connected above the pan fill/drain port, it's unpossible to fill this way...www.landroverworld.org
I opened my Atlantic British rebuild kit (never used it; I've got it for sale in the sales section) and the standard gasket was ripped from the factory. That's all I needed to order the Lubelocker gasket... which I also wound up never using and is included in the sale.