The Benefit Service has a number of online forms and calculators, simply select the one you want.
Appeal a Benefit DecisionApplication for Council Tax Reduction/Housing Benefit
Benefit CalculatorBenefits Checker (Gov.uk)
Discretionary Housing or Hardship PaymentReport Change in Circumstances
Submit Online Benefit DocumentsStatement of Reasons Request
Universal Credit - ApplyWhen will I reach state pension age
The following PDF form can be filled in - you must save the form and upload it using Submit Online Benefit Documents.