The queen isn't sovereign, the Crown is. And then, that's only over matters strictly on the "international plane"; in matters of domestic policy, parliament is sovereign.
The queen still formally signs laws, as in Royal Assent (that may formally be withheld), but that's not what sovereignty refers to, which is specifically the ability to make and unmake laws. The Queen no longer has that power -- nor does the Crown.
Like Jackdaw, I feel that she may fall foul of election expenses laws. She is talking about sending support into constituencies, there was a major fuss about expenses for that last year. A few other things caught my eye as well, but details were vague.