Hi Gareth,
The trick is to ignore the dog totally when it's jumping up - if necessary push it back (don't hurt it, obvz) by puffing your chest out and walking directly against the dog. The dog will quickly respond to this knowing that you don't want it to jump up. Then, as soon as (and it's important to be on the ball here, I think) it sits down or stands on all fours and looks up at you, reward the dog by getting down to its level - so that your face to face, let the dog lick your hands, nuzzle your face, etc. Do this a couple of times and the dog will learn not to jump up at you. Be sure to say down at the same time as pushing it back.
Now if the dog continues to jump up at others, you obviously cannot expect them to march into your dog, so you need to distract the dog - e.g. something that makes a noise or poke it with your finger or whatever - again, the moment the dog gets down, you have to reward it (bag of chicken bits in pocket is good).
I am sure you'll be fine
Cheers,
Robin