children & aliyah

My wife who is not jewish & I are splitting up. Rather than fight etc,
she will be keeping custody of the children. Rather than stay in the
uk & make a new life I would like to make a fresh start in Israel. If
I make aliyah & become an Israeli (is olim only a new immigrant btw ?)
& if my children decide, as adults to come to live in Israel will they
need to convert, or will their dad being jewish be enough ?