Vauxhall Zafira Brakes

Im an owner of a Vauxhall Zafira Life Auto, 1.8 petrol 2004. I had all 4 brake discs replaced 8 weeks ago as they had completley worn down. For the last 6 weeks iv had no problems till a fortnight ago. I noticed the handbrake light kept going on and off intermittiantly. For the last week it has been on constant. 2 days ago I went out in the morning and the brakes were playing up rotten. Iv had to completley floor the pedal for the car to stop. It does stop but if I really have to hit it hard you can feel juddering coming from under the bonnet. I dont have a great knowledge of cars. Does anyone have any advice on what it could be. My hubby has tried to check the brake fluid level but it is in the most inconvenient place and he hasnt been able to reach it to check.