Just another question ...
Will it work that the assests are split 60/40, 70/30 or whatever, then the next element is the CM of 20% of my salary. On top of this am I still expected to make a payment to my ex wife for her needs ??? or is this included in the above figures
Taylr14 hits the nail on the head; it all depends on individual circumstances. The 50:50 split is the 'yardstick of equality' and the idea is both parties get half of the assets adjusted as necessary so as not to cause either of them undue hardship.
In the usual case of the wife and mother having primary care of the children and there not being enough capital to split evenly at the time of the divorce without causing undue hardship, the capital split is topped up by 'spousal maintenance' from the party that has the opportunity to recover from court-induced penury; ie the father. This spousal maintenance has nothing to do with child maintenance.
Child maintenance is beyond the power of the court and as such it would be prudent to ensure that it and the spousal maintenance are kept as two separate amounts and clearly defined in any negotiations.