Using my recovery key to get passed the activation lock on my iPad?

If you generated a recovery key, you removed yourself from Apple's recovery system.

Apple can't help you.

How to generate a recovery key - Apple Support

Using a recovery key is more secure, but it means that you’re responsible for maintaining access to your trusted devices and your recovery key. If you lose both of these items, you could be locked out of your account permanently.

Good luck

As outlined by Johnathan Burger, in activating a Recovery Key for your iPad, you have assumed all responsibility for maintaining access to - and recovery of - your AppleID account. If you are unable to resolve access, you may be permanently locked-out.

Here are the Apple support pages that outline the Activation Lock - and the only mechanisms by which it can be satisfied:

Activation Lock for iPhone, iPad, and iPod touch - Apple Support

Turn off Activation Lock – Apple Support

As you will discover, unless you are the owner of the AppleID that was last used to activate the device, you’ll not be able to defeat or bypass the Activation Lock. With documentary evidence that you are the original owner of the device (such as sales receipt showing the serial number), Apple may be prepared to assist - otherwise they and nobody here will be able to help you.

If you have the necessary documentation, Apple have recently introduced a new portal though which you may be able to request release of an Activation Lock:

How to remove Activation Lock - Apple Support & start an Activation Lock support request.

However, in your circumstances, be aware that you may need to create a new AppleID to reuse your iPad.