No that is not the case - especially if the Inheritance is received after the Divorce has been issued.
The court will only take account of Inherited assets where there are insufficient funds in the other assets to meet the needs of both parties.
In your case if the assets were sold then whilst your wife would receive a larger share of the joint assets your actual inheritance would be safe.
Indeed even if you had already received the Inheritance this would be the case (assuming you had always kept it separate from any other assets).
Your mother can certainly look at setting up a Trust within her Will.
However any trust from which you will benefit will run into the same problem - and whilst it could benefit your sons the Trust could be challenged once they were both over 18 if they wished to force an immediate distribution.
If you trust your brother implicitly then your mother could gift her monies to him on the basis that he will settle with you when the divorce is over; but my suggestion is that you move on the divorce immediately and start the financial negotiations.
If not then yes a Family Will Trust will be the next step.
Please ask if you need further details