Open Question: please could you help?

Hi please could some one help me my dear mum passed away 3 months ago as far as I no she didn’t make a will my brother never married and always live with my mum he cared for her for 7 years before she died with my help with washing house work ect and also carers who came in to wash change her. My mum only had her house to leave us but she wanted my brother to live there when she died and I feel I would want to stand by her wishes but would like my brother to have to give me the £16.000 he promised me. During the 7 years my brother cared for her he saved up £40.000 out of her pensions that was left over after the household bills and food was paid for but he put it in his saving book in his name he told me that I could have £16.000 of it when mum died as he was having the house. Now he says he wont pay me it so I feel cheated by him please what do I do about this please? How do I go about going to probate how long have I got to do this? And will I have to pay any money out to go to probate as I have not got much money to spare. Thanks Diane.