what was his relation with the british?
They wanted him as an ally.
Draža Mihailović
In January 1943, the SOE reported to Churchill that Mihailović's subordinate commanders had made local arrangements with Italian authorities, although there was no evidence that Mihailović himself had ever dealt with the Germans. 
what is ba congress? It was a meeting of representatives of Draža Mihailović's Chetnik movement between 25 and 28 January 1944 in the village of Ba in the German-occupied territory of Serbia during World War II. what was its objective? It  aimed to advance a political alternative to the November 1943 Second Session of the communist-led Anti-Fascist Council for the National Liberation of Yugoslavia (, AVNOJ) of the Yugoslav Partisans. who were it participants? They were from Serbia, Montenegro and Bosnia together with two or three Croats, one Slovene and one Bosnian Muslim. when did the leader join the military? October 1910. what was his rank in the military? Colonel. when was the chetniks formed? 1941.
wiki:13363311
Draža Mihailović [SEP] Relations with the British
On 3 January 1943, just before Case White, an Axis conference was held in Rome, attended by German commander Alexander Löhr, NDH representatives, and by Jevđević who, this time, collaborated openly with the Axis forces against the Partisans, and had gone to the conference without Mihailović's knowledge. Mihailović disapproved of Jevđević's presence and reportedly sent him an angry message, but his actions were limited to announcing that Jevđević's military award would be withdrawn. On 3 February 1943 Charles de Gaulle awarded Mihailović with Croix de Guerre, a French military decoration to honour people who fought with the Allies against the Axis forces at any time during World War II.