As others have indicated, your mother was free to leave her estate to whomever she wanted to. However you have the right to challenge the will but you would need to convince a court that you should receive 'reasonable financial provision'.
Quote:
"Where after the commencement of this Act a person dies domiciled in England and Wales and is survived by any of the following persons:—
. . .
(c)a child of the deceased;
. . .
that person may apply to the court for an order under section 2 of this Act on the ground that the disposition of the deceased’s estate effected by his will or the law relating to intestacy, or the combination of his will and that law, is not such as to make reasonable financial provision for the applicant.
. . .
In this Act “reasonable financial provision”—
. . .
means such financial provision as it would be reasonable in all the circumstances of the case for the applicant to receive for his maintenance
. . .
. . . the court shall, in determining whether the disposition of the deceased’s estate effected by his will or the law relating to intestacy, or the combination of his will and that law, is such as to make reasonable financial provision for the applicant and, if the court considers that reasonable financial provision has not been made, in determining whether and in what manner it shall exercise its powers under that section, have regard to the following matters, that is to say—
(a)the financial resources and financial needs which the applicant has or is likely to have in the foreseeable future;
(b)the financial resources and financial needs which any other applicant for an order under section 2 of this Act has or is likely to have in the foreseeable future;
(c)the financial resources and financial needs which any beneficiary of the estate of the deceased has or is likely to have in the foreseeable future;
(d)any obligations and responsibilities which the deceased had towards any applicant for an order under the said section 2 or towards any beneficiary of the estate of the deceased;
(e)the size and nature of the net estate of the deceased;
(f)any physical or mental disability of any applicant for an order under the said section 2 or any beneficiary of the estate of the deceased;
(g)any other matter, including the conduct of the applicant or any other person, which in the circumstances of the case the court may consider relevant."
http://www.legislatio...kpga/1975/63/contents
Chris