Bosch Dishwasher SGV4313GB/07 I select the required program and shut the door, at this point I usually hear a click followed by water flowing. Now though nothing is happening the water isn't filling.

If you are able to select wash programs and the panel is responding then most likely the water inlet valve is faulty and needs replacement. I am assuming you are hearing a click but no water comes through. Also check the inlet water tap under kitchen sink.
The valve for your dishwasher should be like this

http://www.bosch-home.co.uk/store/product/Valveaquastop/00263789
However, the problem can be more complicated if your dishwasher uses water softener unit. Will need the full model number to verify this. For example SGU5602/xx
You can also view all the parts at this site http://www.bosch-home.com/us/store/spareparts/Dishwashers60cmbuiltinbuiltunder/SGU5602/03

You may be able to find some info here: http://www.applianceaid.com/drain_wash.html

It is possible that the machine does not start off the cycle because there are errors or feedback from the inputs. For the program to start up the main program controller must initiate the INLET/PUMP MOTOR/DRAIN to work when it is commanded .If this does not happen then the voltage at these points must be checked or the fault relates to no voltage/drive from the controller. This means the controller is a suspect.

Check how to remove the control panel: http://www.espares.co.uk/advice/dishwashers/a/3/1287/how-to-replace-a-hotpoint-dishwasher-fascia-p.html

If the water flows then the flow should be good, if not the inlet valve is bad or there is dirt in the filter. Also check the flow at the inlet of the water line. What is most important for the motor to start functioning is that the door switch must be ON when the door is shut or this will be an error for starting the motor. The water pressure must be good and the spraying must be seen to be good. If there is low pumping or pressure then the spray arms will not turn around to inject with pressure. If so the pump must be checked for clogging.

To replace check this link:
http://www.espares.co.uk/advice/dishwashers/a/3/1293/how-to-replace-the-spraying-system-on-a-dishw.html

It is possible that the machine does not start off the cycle because there are errors or feedback from the inputs. For the program to start up the main program controller must initiate the INLET/PUMP MOTOR/DRAIN to work when it is commanded .If this does not happen then the voltage at these points must be checked or the fault relates to no voltage/drive from the controller. This means the controller is a suspect.

check these error codes.

http://fixitnow.com/wp/2010/09/01/bosch-dishwasher-test-programs-diagnostic-mode-and-error-codes/

If the water flows then the flow should be good, if not the inlet valve is bad or there is dirt in the filter. Also check the flow at the inlet of the water line. What is most important for the motor to start functioning is that the door switch must be ON when the door is shut or this will be an error for starting the motor. The water pressure must be good and the spraying must be seen to be good. If there is low pumping or pressure then the spray arms will not turn around to inject with pressure. If so the pump must be checked for clogging.

Finally after the wash the drain valve will be activated, the water is allowed to come in to rinse and then finally the drain valve/pump activated so as to drain off all the water.

Make sure that a fault in any of the cycle will relate to the specified action, so check the command from the program module and then the executing device be it the valve or motor or pump.

Please check the link below:

http://www.espares.co.uk/advice/dishwashers/a/3

For spares click On:

http://www.espares.co.uk/search/dishwashers/p/1083

Thank you for using Fixya.

Open the dishwasher door if the desired cycle does not perform as selected on the control panel. Press the main power switch "Off" and then "On" again. Select a cycle, press the appropriate button, press "Start" and close the door. Make sure the door is closed completely.

Check the circuit breaker and water supply if the dishwasher does not start after selecting the appropriate cycle on the control panel and shutting the door.

Turn "Off" the dishwasher and disconnect the dishwasher from the power supply if an error code between "E01" and "E30" appears on the digital display. Reconnect and turn the dishwasher "On." This should reset the control panel.

Terminate a program on the control panel by holding the "A" button and pressing "Start" at the same time. The display will read "0:01". Close the door to start the program sequence. The display will read "0:00" when finished.

There is a float under the machine that tells the pump to shut off. If the float is stuck or bad, the machine will keep draining. I am including a web site that might help. Bosch Dishwasher That Will Not Stop Draining Hunker

you have a clog remove the float clean and replacs,sould work now.

Most likely the control unit is defective.

This is generally because of a stuck diverter solenoid. The water goes to the pump and then is either sent to the wash arms or the drain. Also, check the drain.

remove kick plate from below the door. youll see a white tray behind the kick plate there is water in the tray activating a over flow switch. using a towel remove the water. this will solve the problem