You are incorrect when more doses are available and purchased.
According to the current Advent price sheet, with manual production:
If an individual patient has enough DCVax-l and received 10 doses (three years worth), it would cost 250k pounds total.
If a patient has enough DCVax-l and received 12 doses (four years), it would cost 300k pounds total.
If a patient has enough DCVax-l and received 14 doses (five years), it would cost 350k pounds total.