Details of availability of Hamelin's scores may be found at
https://www.sorabji-archive.co.uk/hamelin/scores.php.
Some are available direct from The Sorabji Archive; almost all of those that are not are published elsewhere and their publication details are given in the list.
Pavane Variée is not yet available as it is due to be published soon.
Please address any further enquiries to sorabji-archive@lineone.net.
And yes, copying/uploading/downloading copyright material and/or distributing it is indeed illegal other than with the express written consent of the copyright owner, although the copyright terms vary from country to country; many countries now adopt the 70-year term in which works enter the public domain at the beginning of the 71st year following the composer's death, but it would be so much less confusing all round were every country to adopt the same term.
Best,
Alistair