Some people use to spell songs and names falsely. So, if you're not sure how to spell it, here is my guide:
Memory is always spelt Memory. Not Memories.
Mungojerrie is not spelt Mungojerry. It's Mungojerrie.
Rumpelteazer is diffucult. Her name was originally spelt with "el" by T. S. Eliot, aswell as on the OLC and OBC. And OVC, though her name is spelt Rumpel Teazer there. Her name was later changed to Rumpleteazer, which is now correct, too. So you can choose how you write her name. But, do not write teazer with an s like "teaser". It's Rumpel/Rumpleteazer.
Heaviside Layer is spelt with an i. Not Heavyside Layer.
There is no Gumby Cat in CATS, but Jennyanydots is certainly a Gumbie Cat!
Jemima is always spelt with two m's, and no Jellicle is called Jemina. Unlike the dessert, Sillabub is spelt with an i, not a y.
ALW is written as either Andrew Lloyd Webber or Andrew Lloyd-Webber. Do not leave the "Lloyd", it's part of his surname. Andrew Webber would be so wrong. And it's Lloyd. Not Loyd, Lloid, Loid, Loydd or whatever people use to write.