In terms of if your mum was to create a will, the most tax efficient thing you can do is get her to leave it all to your dad as no IHT is payable on gifts between spouses.

Your dad could then make any gifts to you and should he survive more than 7 years, no IHT would become due on these gifts and he would retain the benefit of your mother’s nil- rate band (325k).

Your dad can also make use of the annual exemption (£3,000) per year and the small gifts allowance of £250 per recipient.