I got a 4 year old Octavia with no spare wheel but a bottle of Copydex and a compressor thing. 

 

Utterly ridiculous no to have a spare so I got a full size spare wheel and tyre.

 

It may be obvious, but is the compressor thing capable of pumping up the tyre or is it somehow suited only to dealing with the Copydex? If so, I'll keep it but I don't want to unwrap it at the moment as it's quite neatly packaged.

Yes, it is meaty enough to inflate a tyre.

I've been using one as a normal compressor for some years. A nice, compact bit of kit.

I use mine as a tyre pump. It's much quieter than one I bought, now in the bin. Compact enough to carry in the boot. SWMBO got one with her new Kia, also paid for a space saver, so a spare in the garage. 

Yep, its purpose is to inflate a tyre so meaty enough for that. better to buy a full size spare (the do fit in space as my car has a 16  inch  alloy wheel & tyre in there), if you use the tyre sealant for just a a nail gone through then the tyre is scrap any way as you can't/ shouldn't repair them after. the sealant is only really fit for the bin.

Thanks everyone, it sounds like a decent enough bit of equipment and can replace my current electric pump which makes enough noise to be heard in the next street!

I would not rely on one of the goo and pump method of doing a temp repair.  It is pretty doubtful it would be a success and if it were, you probably had such a slow leak you could get tp a tyre depot anyway.