Break pedal hard to push AND grinding noise when braking. What is the likely problem?

Drive a Ford Mondeo 2004 Tdci.

Over the last month every so often the brake pedal would become stiff and a grinding noise could be heard when breaking. This morning it has got worse. I pushed the brake pedal which was very stiff, a grinding noise was heard and I very momentarly seemed to lose breaking power, then suddenly the pedal became ok to push again. This happened several times on the way home. Obviusly I'm not going to drive the car anymore until I have fixed the problem because it would be dangerous to do so.

I know that if a grinding noise is heard while breaking it is likely to be worn disc pads but why would the brake pedal become hard to push also? Am I right in thinking that worn disc pads would not cause the pedal to become very stiff?

I've read that the stiff brake pedal might be a result of a faulty vucumm pump, but why the grinding noise?

Although I have never changed disc pads I'm happy to attempt to change them myself as it doent look like it is too difficult a job, however I don't want to spend money on new pads and waste my time if this is not the problem.

Any help and advice would be greatly appreciated, Thanks!

You need to replace the brake pads as they are worn out and as you did not check the condition of your vehicle regular you also have the expense of replacing the discs as well.

Are you freaking serious? The sound you hear is metal grinding on metal. You may not like the fact, but cars need routine maintenance. Take the car to a shop for crying out loud.

You brakes are wearing out. Get them in the repair shop at once and save yourself an accident or an expensive brake job.

Sounds like you've been driving with bad brakes so long that the caliper pistons or slides are frozen! The next thing that happens is that the pistons blow out of the calipers and the brake pedal suddenly goes to the floor and a truck hits you when you can't stop!