Thats the one. return from heater or loop and the 3/4" ish pipe from the header tank all into the bottom hose on the rad, if you are short of hose t pieces there is a double version of the one below. But i cant find it . keep the header tank as high on the baulkhead as poss.
http://www.ebay.co.uk/itm/51mm-2-OD-...item4cf7164888
Bob