Two quick point here, first tablet vs netbook:
My last post was only short and I didn't give a real reason to choose a netbook over a tablet; a physical keyboard, generally better spec (I agree that maybe sacrificing spec to conserve battery may be good in some situations but I suspect in context to the question this device won't be used much outside the house). But mostly it's the keyboard. Of course I would recommend a laptop over a netbook, the other relevant factor seems to be cost, of which a netbook certainly for fills that over a laptop, though you can get a decent laptop for under £300.
Oh but this quote; "the safety of a Windows operating system can't be underestimated I'm afraid." really did make me laugh, Android, any flavour of Linux and even the deplorable apple OS (as it's rooted in BSD/GNULinux) are more secure than windows.
Onto the other post about WoW. Sounds like you have an internal issue more than anything, like if this is a home network, and I assume these are children you're trying to stop plying the game? Why do you allow them to reset the router? Whose paying for the WoW accounts? And if any of that's out of your control (maybe they're not children?) why do yo dislike WoW so much? What harm is it causing you?
As for your actual question though, there are of course ways around it, you could put the router in a locked box

or more seriously you could set up a firewall on a dedicated box (like a server) and route all traffic through it, blocking the offending ports of course, this solution, obviously, doesn't have a reset button. I can only assume the IT dept in Manchester manage it by being the only people with access to their system; there router will still have a reset button though.