Gday
I haven't travelled via airport to Melton for a long while but I know theres heaps roadworks on the turn off the airport freeway onto the ring road. Think it mainly affects traffic going east (and Melton to the west). If you follow map....from airport head towards city (stay in left lane). Take turn off to Ring Road to head WEST (Ballarat, City, etc). Think you go under the Ring Rd overpass and then take turn off (turn off prior to overpass takes you east). But haven't been that way for while so things might have changed. Follow Ring Rd and turn off at Ballarat turn off (Western H'way). Then just follow road to Melton (reckon its all freeway now). Track is on left of highway at Ferris Road turnoff. Wouldnt take more than half hour on a Saturday UNLESS roadworks slow things down but as above most roadworks on easterly direction.
Hotels at airport maybe best bet unless wanna head into city. Theres a hotel at the track but probably booked out by now. At airport theres the big fancy one and also one of those Accor Hotels. F1 or something (Google "Accor melbourne airport"). Bit cheaper than the big posh one. Had friends stay there year or so ago and they said was fine given that they only sleeping there.
Cheers