if i claim maintenance for my 3 year old son would the father have access rights even though he has never seen or wanted to see him ?

In normal circumstances a parent cannot prevent the other parent from having visitation with their child, this is unless there is a restraining order or some other similiar situation in place. If he has never wanted to be involved before it is unlikely he would want to now, but unless there is a specific reason would that be a bad thing. All children deserve to know where they came from and about their relatives and if they are not going to be detrimental to the health and safety of the child I doubt you would be able to stop him.
For more advice try:
http://www.adviceguide.org.uk/ copy

http://www.direct.gov.uk/en/Bfs l1/BenefitsAndFinancialSupport/ DG_10018808 copy

http://www.childsupportguidance .co.uk/ copy

http://www.csa.gov.uk/ copy