Suggpufffairy put your assets in a discretionary trust with your children as beneficiaries. This will mean that only your daughters can receive money from it and if they and their husbands split up it cannot be included in any divorce settlement
Children excluded from their parents wills can only claim against it if they can prove they were dependent on their parents in some way. So, if a parent died leaving a young dependent child whose keep they had been contributing to and then left no provision for them in the will, then the child can appeal to the court for proper provision. If a parent cuts a grown-up child out of a will and that adult child is not dependent on them in any way, then they have to do without and have no right to demand a share of their parent's estate - unless of course they think they had been excluded for one of the reasons mentioned in elegran's post.