If the value of the house is say £ 1 million,would a payment involved?I thought transfers between a married couple were free of any taxes ?
Transfers between spouses are exempt from IHT; this is a totlally different issue to the queries you raise re intestacy.
The surviving spouse is entitled to the deceased's personal chattels (eg books etc); a fixed sum of £250K; plus a life interest in 50% of the residue of the estate (ie what's left).
If she requires the deceased's interest in the house to be transferred to her (value £500K) then if her life interest is less than £500K she will need to pay the difference; if more then no balancing payment necessary.
Is a Will the only way to document the wishes of each of the couple?A Letter of Wishes witnessed by independent parties (say 2)would not be valid?
A "letter of wishes" does not normally conform to the legal requirements of a "will". It is usually just a letter in addition to a will designed to help the executors of the will to effect the distribution of the estate in line with the testator's wishes.
BTW,are online Wills Valid?
On-line wills are valid, again, if they satisfy the usual requirements. However, they can be fraught with problems depending upon who is drafting the will.