No. As things stand, surrogacy agreements are unenforceable in the UK. This is because under English law, a surrogate mother cannot be forced via any contractual provision to hand over her baby and likewise the intended parents cannot be forced to pay money to the surrogate or assume responsibility for the child upon birth.
It follows that any such written agreement or contract will not be enforceable, and a high level of trust needs to exist between the surrogate and the intended parents.