govuk-frontend/dist/govuk/components/input/template-with-prefix-and-suffix.html

GOV.UK Frontend contains the code you need to start building a user interface for government platforms and services.

<div class="govuk-form-group">
  <label class="govuk-label" for="input-with-prefix-suffix">
    Cost per item, in pounds
  </label>
  <div class="govuk-input__wrapper">
    <div class="govuk-input__prefix" aria-hidden="true">£</div>
    <input class="govuk-input" id="input-with-prefix-suffix" name="cost" type="text">
    <div class="govuk-input__suffix" aria-hidden="true">per item</div>
  </div>
</div>