If there's any way you can afford it, do them full-time.
It's not impossible to pass with a distance learning course - I managed it. But it is difficult. The material is much harder than for PPL, and there's much more of it to learn.
Why don't you visit a couple of the schools? Any decent school will be only too happy to show you their notes. Then you can have a good look through, and decide whether you think you'd be able to learn it by yourself.
Good luck!
FFF
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