Married lesbian couple looking for sperm donor. We live in Bristol.

Hi there.
I’m a recently married woman with 2 stepchildren that my wife has from previous relationships. We live in Bristol.
We are looking to expand our family and I would like to find a sperm donor for my wife. Preferably white. Age wouldn’t be an issue as long as they are over 18. We are not looking to co – parent and we would not want the biological fathers name on the birth certificate. This would mean they would have no legal rights and no involvement at all in the childs child’s life