You may try R-Studio before buying it. It'll allow you to do everything in data recovery except saving recovered files even if it's unregistered. But you may preview files to understand if it's worth buying it.
For the disk, the R-Studio's Drives panel should show the 500GB new partition (cloned from the laptop) and an empty space for the rest of the disk. Only files that resided on that empty space could probably be recovered. Scan this space and see what R-Studio finds. Most likely most found files will be among Raw files. Try to preview them to estimate chances for successful recovery. If the results satisfy you, buy R-Studio, register it, and save the recovered files.
For further reading: File Recovery Basics: How Data Recovery Works, Data recovery guide, and R-Studio on-line help.

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R-Studio Data Recovery Software

@Alt, if you read the post right above mine, you will see it is a new poster with 2x 1TB disks,
Cheers

Thank you for your quick response.

Mea culpa! That happens when one tries to do several things simultaneously.

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R-Studio Data Recovery Software