My car is a 2002 Mondeo. Today when I needed to break on a fairly sudden scale I found every time it would make an odd noise and didn't feel like it stopped sharply enough. I can't say for sure how it sounded, but it was a bit clunky noise and came from under the car around where the peddles are. Whenever I braked slowly, it was fine, it was just when I had to suddenly brake or if I was going to fast and had to brake, it just felt like the brakes would skid and lock and skid and lock a slight bit. So I am not talking during an emergency stop style urgency, but if you are coming to traffic lights and need to stop fairly suddenly. I had my MOT in December and all was seen to be fine. 

Any idea what it could be ? Only just got my ignition coils and spark plugs and ABS replaced (I think it was the rear wheel ABS fixed so probably not related to this given the noise seems to be drivers area).

Also, speaking of ignition coils, as mentioned above I got that replaced along with a spark plug as my car was kangarooing real bad, but my car still feels chuggy slightly. No where near what it was before the new coils, as it was jolting all over the place before they were replaced and I can now drive 95% okay, but it just feels like when in lower gear that it is very slightly rougher than it should be. My diagnostic device doesn't show any errors (it did before they were changed). Could this still be the replacement ignition coils, or the spark plug ? I am not a car guy so not sure how they both effect the car. 

Any ideas to all this or suggestions ? Especially the brake grinding noise and sliding.

Not a great help perhaps, but.....

If your rear ABS is playing up you'd detect it at the front, either through the pedal or if it's a problem with the ABS unit, that's also at the front (under the bonnet). So I wouldn't rule that out. It sounds like the ABS is oversensitive, but I'm afraid I don't know what could be causing that.

Years ago my brother had a problem on his Audi TT with the abs kicking in when it shouldn’t. Turned out to be a faulty swerve sensor. Garage fixed it and that is what they said it was.   I do not know if all cars with abs have a swerve sensor.