Banning adverts is an interesting idea. I am not sure there is such a clear dividing line, though, between what is an advert and what is not. I am inclined to think that any activity which promotes a specific view or views, or a specific candidate or candidates, counts as advertising. A public meeting involving all candidates is, arguably, not an advert. A media interview could serve as an advert. A book or report may not itself be an advert, but perhaps there would have to be a ban on advertising books and reports pertaining to particular candidates and parties. Leaflets about particular candidates are surely adverts (they are just mini-posters). Newspaper reports which mention some candidates and leave out others, are, arguably, adverts too.
Perhaps the ban needs to be a more radical one - at least, to make it more amenable to debate. Too radical a ban might favour the existing government, as they'd be the only politicians anyone had heard of ...What do others think?

{Ed. I think the distinction lies mainly in whether or not the party actually has to pay something.  There are separate rules for the way the media covers political activities, (and maybe we should debate those sometime too), but anything which is over and above the press coverage which the media would want to give anyway, and most certainly if there is money involved, I think that is where we should draw the line.  (This creates problems, of course, with those newspapers which are openly sympathetic to one party or another, whereupon I suppose we must rely on the press complaints council.) Peter Emerson}