Avoid extra sql query

Retreive the applicant email address directly instead of using the
application instance.

app/services/submit_form.rb

@@ -36,15 +36,15 @@ def submit_form!
 
   def create_application_records
     ActiveRecord::Base.transaction do
-      school = create_school
-      applicant = create_applicant(school)
-      @application = create_application(applicant)
+      create_school
+      create_applicant
+      create_application
       delete_form
     end
   end
 
   def create_school
-    School.create!(
+    @school = School.create!(
       name: form.school_name,
       headteacher_name: form.school_headteacher_name,
       address_attributes: {
@@ -56,8 +56,8 @@ def create_school
     )
   end
 
-  def create_applicant(school)
-    Applicant.create!(
+  def create_applicant
+    @applicant = Applicant.create!(
       ip_address: ip_address,
       given_name: form.given_name,
       middle_name: form.middle_name,
@@ -75,13 +75,13 @@ def create_applicant(school)
         city: form.city,
         postcode: form.postcode,
       },
-      school: school,
+      school: @school,
     )
   end
 
-  def create_application(applicant)
-    Application.create!(
-      applicant: applicant,
+  def create_application
+    @application = Application.create!(
+      applicant: @applicant,
       application_date: Date.current.to_s,
       application_route: form.application_route,
       application_progress: ApplicationProgress.new,
@@ -100,7 +100,7 @@ def delete_form
   def send_applicant_email
     GovukNotifyMailer
       .with(
-        email: application.applicant.email_address,
+        email: @applicant.email_address,
         urn: application.urn,
       )
       .application_submission