Fastest return is either a visual circuit or a reciprocal procedure turn.
Visual Circuit: If continuing fire at 1500', take control/announce intention, push to level, F1/set MCT/activate approach phase (option to SEL higher SPD), turn DW/activate secondary, continue ECAM, stop at STS, after T/O CLB c/l, brief brief, NITS done as PA (if no time, phone CM/CC first if time), read STS, ECAM actions complete, mention QRH c/l and after LDG intentions, F2/turn base...
Reciprocal: Might have to climb higher if in IMC to self position for IAP, would start procedure turn about STS page.
That ticks all the boxes, but all you need to do is 1) try and put out fire, 2) not hit anything, 3) put the gear down, and 4) stop before the end of the runway.