How can i find my brother without payin a vast amount of money!?

my dad has a son n he only told me about him 3 years ago,my dad has visited him on a few occasions but when i mention that i want to meet my brother and that i want him in my life my dad says that he doesnt want me to meet him,maybe me looking for him my self is the wrong thing to do but that is the only way i'll ever get to know who my brother is...im prepared for the unacceptance that i might get but i still feel its something that i have to do,i live in the uk and its hard to find someone in the uk on the cheap like.could someone maybe recommend a website on where i could get a bit of help finding him,ive tried chatting with my dad but he changes the subject all the time,i cant see there being any problem to be honest but theres some reason...am i stupid to look for my older brother when my dad has said he doesnt want me to see him?by the way im not a little school kid im 20 yr old!