im trying to find my brother Andrew Harvey ive had no luck and been to all different sites Andrew is my half brother he was born in the year 1989 and our mum was Sandra joan young and my real dad was john Stephen lange my step father was called Robert a Harvey ive got brothers which are named Stephen terrance lange and brian phillip lange
last I knew was Andrew was in wathem forest in London and since than ive not found him

Perhaps you mean WALTHAM, not wathem. Correct spelling is vital.

Because his name is not unusual, you really need a birth date.
It would help to have birth dates (and locations at birth) for each parent and sibling too.
Make clear who are the biological parents of each child.
Sometimes the best place to start is not online, but small town newspapers.
Are you close enough to London to look in person, and do you have a car?
Good luck. This is a job we can give advice on, but not do for you.