Yes, I understand that a temporary plug is only a temporary fix, until a permanent repair or replacement tyre can be fitted - and this process has worked pretty well in the past. Previously, the AA man put a temp plug in and I trundled happily home and then to the workshop the next day. But this time, I found my tyre flat and it was Boxing day, so I thought it would be better to get a temp fix rather run around with a nail in the tyre for a week or so until the workshop reopened. But it didn't even seal the leak, and has made the tyre unrepairable. And ironically, the weather was so bad I hardly used the scoot in that week!
So, my dilemma is that the gunge... should...mean that I'm never way waylaid by punctures again, but if it doesn't work, then you are in a worse mess than before!

That's unfortunate it didn't seal but that's what can occasionally happen with the temp plugs. I've seen that many times. At least with PunctureSafe it can be washed out of the tyre and a conventional repair carried out if you wanted at a later date. But really, it shouldn't be necessary. For me it's simple. PunctureSafe is superior and proven always. Just make sure to read and understand the instructions so it works.