govuk-frontend/dist/govuk/components/input/template-with-prefix.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">
    Amount, 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" name="amount" type="text">
  </div>
</div>