I have hit them with all my weapons,and magic, fireballs, dispel magic etc so how do you get past the green and ochre jellies without losing everyone ? Anyone got any suggestions please?

To my knowledge, magic and missile weapons are ineffective against jellies. Your best bet is using swords, axes, etc.--anything that cuts, slashes, dices, or slices. Of course, you will need to do this fast (before the jellies nail you with poisonous gases). The faster you send your warriors up close to engage with melee weapons, the sooner the jellies will be compelled to launch a physical attack (not gas), which is what you want (does your best warrior have boots of speed?). Usually, two warriors (or one with much resistance to poison and a good axe) will do the trick.
Good luck!

Thanks very much. I'll give it a go!

You might want to try arrows of fire and arrows of ice on the green ones or weapons for bashing, like a war hammer+1.

THANKS EVERYONE, I HAVE NOW KILLED THE JELLIES !!!!!!!