Sorry the previous answers are wrong. Scottish law is different.
In Scottish law the children do have a right to a share in the moveable estate regardless of what the will says.
If your father is dead you and your sister between you have a right to half the moveable estate - so I would guess that means you get a quarter and your sister gets the rest.
To claim just advise the executor - you only need to go to court if the executor won't pay up.
You sure dzug? so what's the naffing point in having a will, surely his mum wanted to leave it to his sister, and this question and attitude is a good indicator of why.
Lifted straight out of the 'Which' Guide, R1geezer, so yes I am sure.
The point of a will? Well, you can do what you want with the remainder of the estate. The 'legal rights', as they are called, in this case only apply to half the moveable estate - the rest can go wherever you desire.
Similar in many other countries - for example in France I understand you can't disinherit your family either.
The principle I suppose is that you are responsible for your family whether you like it or not.