The wonderful thing about this is that there is only person who is going to be happy (Tom). Everybody else has something to be offended about.
Lilian and Jennifer (and Brian and Matt) - nothing for their offspring, and they get nothing either - they don't need the money, as Peggy pointed out, but we all know that feelings can run very high in these circumstances. I can't see any of the grandchildren in these two families making any fuss directly but privately I expect several of them will be rather miffed because of Tom. If they'd all been passed over in favour of the Borsetshire Cats' Home, it might have been easier to stomach.
Pat and Tony - they could do with the money but will get nothing and neither of them is ever slow to take offence, especially over the disparity between their material success and Tony's sisters'. They're already unhappy about Tom's plans for the business and they now have very good reason to be worried about Helen. They will be really, really upset about this will.
Helen gets the house, lovely, but she's not being treated equally with Tom, and she won't like that.
Kirsty's hit the jackpot, hasn't she! As somebody said upthread, I wonder what Brenda will think about it all?