Yes. You can pay a lump sum (the Plan Prepayment) at any time to reduce your monthly payments to the Nominal Rate of £1 per month.
The Plan Prepayment amount is fixed in your contract, so there are no surprises. In year 1 the amount to pay is the original purchase price of the boiler quoted by your local gas engineer, decreasing annually down to zero after 12 years.
If you wish to continue with BeWarm service and maintenance cover after paying the Plan Prepayment, you can choose to pay an additional Service Charge of £9 per month.