Well, Strangemaggie, I'm kinda in a similar situation -- years ago I used to do quite a bit of film photography, got away from it, now do projection art, which is neither here nor there -- but I picked up a Diana at a flea market and thought why not? This has prompted me to get back into film photograph, with a SLR though. I've procured some film for the Diana and the results have been fun and interesting, especially so as a fresh creative addition to the projection art. However, as far as photography specifically, I see the SLR I just bought as more beneficial.
That said, I've seen some really fun, interesting stuff come from, actually a Holga, but it's the work of a fella who is a very good photographer. He perfected his skill set on a SLR, I feel that his previous SLR experiences have really enhanced his Toy Camera work.
Back to the Diana project... I set about it with a specific project in mind and specifically have sought out the subject, with a fairly clear idea of what I want out of the Toy Camera (I'm keeping a journal with the pictures, notes, etc.) So for me, this approach is working very nicely, and I'm most satisfied with the results.
By the way, you can set the Diana or Holga up to use 35mm film, if such film is easier for you to obtain. (There may be instructions here, I've not searched...) And the results are fun too!
So release the inner-kid-in-ya!