Make total field readonly

app/views/form/_numeric_question.html.erb

@@ -1,5 +1,6 @@
 <%= f.govuk_number_field question_key,
     hint: { text: question["hint_text"] },
     label: { text: question["header"].html_safe, size: "l"},
-    min: question["min"], max: question["max"], step: question["step"], width: 20
+    min: question["min"], max: question["max"], step: question["step"],
+    width: 20, :readonly => question["readonly"]
 %>

config/forms/2021_2022.json

@@ -1168,7 +1168,8 @@
                   "hint_text": "This is the total of rent and all charges",
                   "type": "numeric",
                   "min": 0,
-                  "step": 1
+                  "step": 1,
+                  "readonly": true
                 },
                 "outstanding_amount": {
                   "check_answer_label": "After housing benefit and/or housing element of UC payment is received, will there be an outstanding amount for basic rent and/or benefit eligible charges?",