Any information submitted through the petitions or contact form will not be passed to any third parties. It will be used for the specific purpose for which it was intended, and nothing more. For example, if you sign a petition your information will only be used in the support of that petition.
Post codes are required for petitions for the purpose of giving them more legitimacy. If people give their post codes it appears less likely that the petition is made up of fake signatures.
Communications will be sent in the case of any important updates on petitions to those who submit their email addresses. Those who submit their email addresses will only receive communications for the petition(s) on which they submit their email addresses.