Surrogacy is not an area of family law that I deal with, but a recent news story caught my eye:

http://www.dailymail.co.uk/news/article-1375861/Child-custody-Couple-ordered-pay-surrogate-mother-monthly-baby-wont-meet.html

Two points emerge.  1. A surrogacy agreement is not a contract enforceable in the courts.  2. The child support system is inflexible to the extent that if you’re the biological father you pay maintenance for the child even if the surrogate mother changes her mind and decides to keep the child.

Something for Parliament to have a look at, perhaps.