@Lauren for start you need alout damp area to dry. Then work can begin. Easier way to check if is dry run dry cloth over and check for residue. Other way there are damp readers in around 40£ what will give you a better answer as they read moisture amount in serfice. If is dry any water resistant product will do. Personally I will use unibond product for painting exterior walls on brick. Its a moisture resistant clear silant. Then after dry you can aplay new plaster. Just make sure damage area was taken down minimum 1 feet farder to insure there is no loose surface left. Hope this help
Hey @PetersHandyManServic Thank you for answering this question 😊- I shall make the team aware so that they can post it live on our blog.
Once complete ill share the link here too so that you can use it on your profile/socials/website etc too