In the first instance there is an obligation on the parties to a dispute to attempt resolution without litigation via Alternative Dispute Resolution (ADR).  If this is not possible court proceedings will be necessary.

If you are an interested party (executor or beneficiary) you will probably receive a letter about the dispute and be invited to take part in ADR and/or subsequent court proceedings.

Yes. A Will can be challenged on the ground that at the date instructions were given and/or the Will executed the testator lacked capacity.  Medical records, witness evidence and expert psychiatric evidence is likely to be needed to prove the claim.  

They will hear cases such unfair dismissal and wrongful dismissal, claims for redundancy payments and/or unlawful deductions from wages and discrimination claims under the Equality Act amongst others.

A farm  that has been inherited by one spouse may be regarded by the court as a non-matrimonial asset, whereas land purchased by the spouses during their marriage could be considered a matrimonial asset. This can be an important distinction in determining whether assets are shared, say, equally or only to the extent necessary to meet needs. This is a complex matter and legal (and accountancy) advice should be sought.

The non-inheriting spouse may not be entitled to an equal share of the farm on divorce but their needs (and those of any minor children) must be met.  They may need capital to house themselves (and any children who will not continue to live on the farm), plus income and pension provision.