Any ideas why my Currys CID45B13 dishwasher won't let me select a wash cycle?
Here is the service manual for your dishwasher:  

http://www.buyspares.com/images/mediator/1513/service%20manual%20-%20cid45b13.pdf

If the control panel is lighting up and giving you some sort of code, the service manual will help you determine where the problem might be.  Sometimes the dishwasher won't allow you to do anything because it detects a fault in the system somewhere.

Also, on page 24 is a diagnostics routine.   Read about the diagnostics and then run them to help isolate the issue.

If you are unable to run the diagnostics, then your control panel is probably the culprit, because the switches on the keypad aren't even working to the point of letting you run the diagnostics.

The service manual should get you going down the right track.