Hello, Graham

I also have difficulties with writing new songs all the time.
I am not using a recording application, but I am using notes of music sheet.
I write down the floated melody (usually about 2 bars) immediately in the memo.
Afterwards, I start composing on the piano with motifs I especially like from the memo.
Various music theories I have learned in the past are useful at this time.
Also, I go to the site where lyricists gather, and I will add melodies one by one at random to the lyrics they wrote. Of course, there are almost bad melodies, but it doesn't matter.
They are not recorded at the time. Because the main purpose is to practice melody making.
I do such things on a daily basis.
I am glad if it becomes your help.

Best regards.

Shigeki Adachi