Yes. Any documents which the surrogate is invited to sign should be in her own language. The intended parent(s) will need to engage the services of a notary to go through any documents with the surrogate in her own language and the notary will then produce a statement setting out all the circumstances of the case.
More importantly, the intended parent(s) need to give thought to how they will get the baby back to the UK and we would strongly advise intended parents in this situation to seek advice from an immigration specialist, not only in the UK but also in the country where the surrogate resides. Certainly, it is advisable to get any paperwork in place in good time.
Sometimes it is possible to apply for an emergency passport and return with the child straightaway. A lot however will depend on whether the child has a genetic link with at least one of the intended parents.
It is not unheard of for intended parents to get stuck overseas with their new baby for prolonged periods whilst waiting for issues concerning immigration to be resolved.