i would love to find my real father

i have never known my real father, i have always felt something is missing in my life, even well before i knew i had a different dad to my sisters and brother, for one i look different to them but was always told it was because i looked like my mum, which i do, but i didnt feel right it's very hard to explain. then as a child i over heard a conversation between my nan (whom i loved dearly) and my aunty saying i had a different dad to the others, needless to say they retracted all they had said, but it was too late and so i asked my mum who said it wasnt true, i am now nearly 52yrs old and i am hoping it's not too late and he's still alive, if he isnt i would still like to know more about him, maybe have a photo anything so i can be whole again, i mean he must have had another family and maybe out there i have other sisters and brothers? all i have is his name and the place he used to live, i dont even know if he's ever seen me or if he cares about me, i have 4 grown up children and 9 grandchildren and i would like to tell him/them about each other at the end of the day he's there grandad/great grandad. i need help to know what to do to find him, i can get basic info from my mum, but just need a helping hand as to where do i go from here, if someone could help me i would be extremely grateful.