Plus in the UK Maternity leaves are very good. <== true but different companies have different clauses to the maximum time.
Agreed, thats why I used the term 'upto' and did not say "All Companies" either. Sure the companies have different clauses for maximum time, but that doesnt take away from the fact that the minimum Ordinary Maternity Leave stands at 26 weeks regardless of who the employer is.
the companies "actually" don't pay from their own pocket
Since you want to get a bit specific about it, yes they do "actually" start by paying from their own pocket. Employers can then claim 92% of that sum back and 100% if they are eligible for small employer's relief.
you get paid 90% of your salary for the first month and the for the next 2-3 months max the govt. gives you around £400 per month
That is the statutory maternity pay that you have outlined and is a minimum entitlement. The rate of SMP is 90% of the woman’s average weekly earnings for the first six weeks (not the first month) and then the lesser of either £100 a week or 90% of her average weekly earnings for the remaining 20 weeks. As you yourself said, that depends on different companies on weather or not to just stick to the statutory. While they are not required to give more than the minimum, many do give over and above and upto the "full" salary.