A F8 fault relates to the heating circuit, normally a failed relay on the PCB, you can get a new PCB here, however you will need an hotpoint engineer to come out to programme the new PCB.
With regard to why the pump is running this is probably in a fault state so the pump is running to clear any water out of the drum for it to release the door lock, it also suggests possibly more is wrong with the PCB than the relay.
In support of college James - any service engineer can reprogram the pcb if they have the necessary smart card however in both cases the cost of the repair will exceed the value of the appliance. However, check your warranty as in some cases that model has got a two year warranty rather than the normal one. (they were sold as special deals by some retailers) If you need a company to carry out a repair on your own board drop a note to -***@******.*** - with a picture of both sides of the pcb.