$1:
Considering she is Canada's Queen, I'd hope she'd use some of the visit to lobby for Canada.
That would be inappropriate under the circumstances of her hosting them on a State visit to England. She would be representing Britain, not Canada. During a State visit to Buckingham Palace it's not her place to lobby for anything for Canada nor for any of the other 15 sovereign countries that she's the monarch of, only for Britain. The Queen doesn't do any lobbying anyway, that is left up to the heads of state of the governments of the individual sovereign countries that she is monarch of.
Further to this:
http://www.independent.co.uk/news/world ... 18430.html$1:
Barack and Michelle Obama will pay a state visit to Britain between 24 and 26 May, in a trip designed to underscore US ties with Britain, and lay to rest more general doubts about the importance Washington accords to its European allies.
Details of the programme have not been released, but the Obamas will be the Queen's guests at Buckingham Palace. The President will hold talks with David Cameron and, if precedent is any guide, may also deliver an address to Parliament.
The invitation to Mr Obama, formally announced by the Palace in July 2010, was passed on by Mr Cameron during his first prime ministerial visit to Washington that month. Downing Street said Mr Cameron was delighted by the visit, calling it a sign of the "strong and enduring relationship between our two countries".......
.