As has been said before, it is subject to the terms of the will. You can obtain a copy by writing to the York Sub Probate Office and Duncombe Place, York with �5 (I think) cheque payable to HMPG. The will is your starting point and it depends on the wording. Unless there is very specific wording though, a predeceased's beneficiary's share fails. Assuming the share has failed (and it is by no means certain), it is then a question of construction as to whether the failed share is shared out between the beneficiaries under the will or the deceased testator's kin under the intestacy rules. If the latter, your wife should share.
The 6 month time limit applies to claims under the Inheritance Act or claims for rectification. A claim such as this could be governed by the Limitation Act 1980 which would put the time limit at either 6 or 12 years depending on the exact circumstances. However, if there is a breach of trust, the time limit may not apply.