Its brake fluid not oil . I disagree about not bleeding the brakes . While your changing the dics and pads you might as well change the fluid as well . Get 2 litres of DOT 4 , it's alot more than you will need but it's always better to have more than enough than too little .
You don't need a brake bleeding kit . I always do mine on my own . All you need is length of tubing running into a jar thats already filled with some old brake fluid . One end is attached to the bleed nipple , the other end is in the jar with the end in the fluid to stop any air being sucked back .
It is easier if you can get a mate to give you a hand though . One cracks open the bleed nipple the other presses the brake pedal . After each press of the pedal ,with the pedal at the bottom your mate then nips up the brake nipple then you release the pedal . Repeat this a few times until the fluid runs clear i.e. no bubbles . Keep an eye on the brake fluid level after 3 or 4 pumps of the pedal and top up accordingly .
Just be aware that the bleed nipples can and do snap pretty easily if you overtighten them . They just need nipping up , not swinging on the spanner , lol .