I'm not a legal expert, but the following have occured to me.
If you don't expect to spend anything inhertited from your father but to pass it all on to your children, why not perssuade your father to leave his estate directly to them. Alternatively, you can pass any inheriage on to them on the death of yopur father (I believe its by "Deed of Variation") so that legally, it is never yours.
One scenario you need to consider - what if you die before your father? At present, from what you have told us, your ex will probably inherit the lot.