Andy
You are at the point where you need to teach the "Walk at Heel".
I've copied a previous post i wrote;
The heel can be tough. I know that people erroneously believe it to be one of the easier commands, but is isn't. The heel is control, and it is a command that really needs to be instilled. It is what keeps a dog safe and under control.
If a dog comes when called, and heels properly it's almost enough by themselves if the dog learns no other commands.
The end result is that the dog should heel naturally without command or use of a leash, and be commanded to move off, or released from the heel without a leash.
Put them on a 9'-12' leash and keep a loop in your off hand. when they begin to pull on the leash, or move in a direction you aren't, drop the loop and immediately change direction, 90-180 degrees. Don't pull or yank on the leash. Drop the loop , change direction and keep walking at an even pace. They will be momentarily off balance from the release of the pressure when you drop the loop, and will have to move in the new direction to regain their balance. Keep a loop in your hand and change direction every time they exerts pressure on the leash. When they yield and changes direction walk backward encouraging them. Give them the come command and kneel and praise them. There has to be reward
Each time you change direction give them a short whistle cue. I use two quick whistles when I change direction. It means to the dog, Pay Attention to me! It's not the "Come here" whistle, it's one where I want there attention on me. When you change direction in the woods grouse hunting, this is the same signal you will want to give them to move in the same direction as you are, even though you may be a couple hundred feet apart. All of my Vizsla's have been very communicative. I communicate with them constantly during training and hunting, either by voice, whistle, clap, or slap on the thigh.
I like to use the longer lead, 9'-12'. I keep a section of the lead in my left hand ,and have the remainder sort of loosely looped in my right hand. There is enough lead in my right hand though to twirl the excess lead in front of my dogs nose. If they start to move forward they get a little"bip" under the jaw. Nothing harsh just the weight of the lead.
When you do the heel to the left, expect that they won't pay attention. You are going to purposely run into them with your knee, once again no rough stuff like purposely kneeing them. You are just going to "walk through them" and keep going. It's very planned. Work them in a "square" to the left a few times and then the right. Eventually you put everything to together in a random sequence. Don't let the dog pick the direction. Walk them up to the house, or car at th eheel. if they start to anticipate ans pull towards the objective, do a 180 and move them off in the opposite direction and then bring them back until they stop anticipating and pulling.
At some point they will just sit down, or refuse to move. They are confused now,and don't know what to do. When this happens take a Big Step back on their training. Talk to them, soothe them, and then gently move them off in a straight line at the heel. They're done for this session. finish on a positive.
The end result is a dog walking at your left knee. His shoulder should be even with your knee, and there should be slack in the lead. Vizslas will pick this up very quickly. They "generally" pull because they've been allowed to get away with it. Once they're no longer allowed, they change their behavior fairly quickly and adopt the new behavior.
As for the leg cocking, when he's on that leash. He's on your terms, not his. He starts cocking that leg, pull him away unless you've commanded him to do his stuff.
we still go back to this method when he 'forgets' to walk nicely and he soons learns. 
