You have applied for a caveat which allows you time to gather evidence regarding the validity of the claim within 6 months. This can be extended but ultimately you have to prove the will is not valid.
If you try to extend just to gain an additional pay out then all costs will be awarded against you.
You say you have spoke to your mother several times a day on the phone and visited her, did shopping and helped to wash her.
Yet you also say she could hardly speak at the end and had a broken hip you knew nothing about.
You say they offered to look after her to avoid care home costs and yet the GF was a nurse and took your mother into their home.
She was not related to her and still catered for her.
You say you were regularly visiting but that your mother didn't really care that much for you and was not a good mother.
You say she was underweight, incapable of doing anything, unable to leave or really speak and yet you spoke to her about 3 times a day on the phone. If there was a concern about her treatment you have not said you raised any issue.
You mention solicitors fees as being paid off and yet you are unable to say what work the solicitor has provided.
You assume the brother will take you to court but he will not need to, this will automatically go to court as you have refused to budge.
You have no evidence of the will being invalid and this is what you need to provide to court.
You are fixated on your brother but it is the solicitor to whom you should be directing queries.
Your day in court will be about the concrete evidence you provide about the solicitor and their errors or omissions.
Your mother died last year and the house needs to be maintained and heated etc. Any direct debits she had, will remain in place to cover this and this will eat away into any inheritance. Your share is also eaten away.
The court is perhaps likely to see this as vexatious and throw the book and all costs at you. They would see it as a form of abuse to punish your brother who bears no responsibility for the drafting of the will.
You have avoided providing information about the work of your solicitor etc and selected only posts you wish to ask.
The narrative has loop holes and contradictions and is full of blind calumny and revenge.
Crack on ( as others have said) with your contrivance. I will bow out.