BMW 3 Series pulling + break judder

Hi I have a 68 plate 320D, i have had a recurring problem for nearly 4 months that im chucking money at and not getting anywhere. I noticed when i hold the wheel straight it pulls to the right and when i let go of the wheel, it starts to move to an off-centre-left position and pulls left. When i used my brakes, especially if i braked hard, it would pull to the left. and the wheel would vibrate. I took it to my independent BMW mechanic, and he said it was the wheel alignment, but he doesnt deal with tyres. I took it to halfords, picked it up and the problem still existed...i took it back, they had it another day, picked it up and its still exactly the same. I spoke to my mechanic and he said he'll take it for another test drive. he said the problem still exists but he noticed a brake judder (I hadnt at this point). I got him to fit new OEM discs and pads, and bedded them in as instructed. I then took it to Kwikfit for an alignment soon after. Since I've had the breaks done, I have noticed the judder is even worse, and I'm still having the same pulling issues. If anything its worse than when i first tried to tackle the problem! I am stuck now as I feel I've just chucked a load of money at it and made it worse. My friend suggested maybe Kwikfit still hasnt done a good job of the alignment, and to take it to an reputable independent tyre shop. Is it possible its still the alignment and also that the brake judder has shown up worse with new brakes? FYI I had brand new OEM tyres (Bridgestone Potenza) fitted and balanced back in November, so I dont think its anything to do with tyres themselves. (again though this was done by Halfords via Black Circles...) It is also fairly low milage for the year - bought Feb 25 at 25K miles, has 34K miles now. I've also kept on top of regular maintenance. Either way I am open to any advice or suggestions, as I want to look after my car and its been perfect up until this problem has arose. Cheers,