A couple of tips:
As wodin said, fighters are not much use in the early war. They are unable to do any damage to enemy units (although they can reduce enemy efficiency). Right now what you probably need most is boots on the ground, i.e. infantry and garrisons. As you've noticed, it takes a while for the British to mobilise. Your forces are well entrenched in Alsace Lorraine, your priority should be to try to protect your flank to the north.
It may be too late, but if you can, garrison your key vulnerable cities, and shift your forces north. If you have spare cash (I know that's not likely) it might be worth investing in rail capacity for the French, to allow you to redeploy your forces from the south to the north more easily.
I wouldn't bother trying to attack in the south, you have bigger fish to fry.
If the Germans have bypassed Antwerp, you can keep it supplied from the sea. A fully supplied fortress on the coast behind the German flank will be a major thorn in their side, and may force them to hold back on the advance.
< Message edited by Myrddraal -- 11/14/2012 1:27:27 PM >