You need to contact Citizen Advisory Bureau in your area or Law Centre. I previously thought that even if you are not in marriage then you should be able to apply after three years but recently I was watching Television and one of the Solicitor said that you will have to spend 5 years before applying for Citizenship if your marriage is finished. I also believe that in order to apply on three years basis your mother need to send her spouse passport with the application. Call home office on this number 0845 010 5200

You have not mentioned your age so I am not sure what will be your situation. If you are in a lasrge city then you will have better chance of getting free legal help from one of the place I mentioned above. You can also call the Citizen Customer Service line of Home office and they will be able to answer your question.

im 19 years old and am still in full time education

Thank you for giving me your age but other questions still need to be answered like when you were born your father was british or not? I will answer to the best of my understanding but make sure you check this from Home office or Law centre.
 
Just from my knowledge you will need to apply on your own unless you are already British because of your father. If you are not already British Citizen then you cannot be included in your mother's application and will also require 5 year residency period compared to three years for your mother.

Someone correct me if I am wrong here.  Only children who can be included in the application have to be under 18. You will have to make your application by yourself after 5 years of residency unless you are already British because of your father.

Here is the text from Guidance notes:
http://www.ind.homeoffice.gov.uk/ind/en/home/applying/british_nationality/application_forms.Maincontent.0004.file.tmp/Form%20AN%20New.pdf
Page 18
If your children are already British citizens you do not have to
complete this section ? go straight to section 3.
Give details of your children under 18 years old who are not already
British citizens and who you want to become British citizens. You will
need to pay a separate fee for your children ? please see the fees leaflet
for details.

my father isnt british and passed away nearly 10 years ago. I thought i may be included in the 3 years bit because the only reason i was granted entry to the uk was because my mother was married to be a british national for over 9 years and during that period we lived in the uk together for over 3 years. I came to the UK when i was 15 as well. would that help my case?

I appreciate you putting faith in my suggestion but you must check with Citizen Advisory Bureau(CAB) or Immigration Solicitor. As far as I know your application will be separate because of following things:

1. Since your Indefinite, you have reached the age of 18
2. Your father was not british and you were not born when your mother had indefinite stay in UK.
3. It wasn't you that came on the marriage basis(it was your mother).  If you were under 18, you could be included in her application.

Solicitors do have access to latest knowledge and they might even try something that I am not aware of. Definitely call the CAB or try legal help from Law Centre.  These are free advice if you live in a large city, they have Law Centre.

Waheed

Probably a bit late to reply now, six weeks after the original post, but it appears to me that you and your mother will both be eligible for naturalisation after 31 January 2007 - the fifth anniversary of your arrival. You can download application and guide AN(NEW) (which gives full details of the requirements) from www.ind.homeoffice.gov.uk/applying/nationality/formsandguidance

My mother and I came to the uk on the 31st of january 2002. We came here due to my mother being married to a british national. We received idefinate stay to remain on the 23rd of Februay 2003. My mother then got divorced 9 months ago. We both also have life in the uk test pass certificates. We were wondering if we were eligible for citizenship now?