If I were Donald Trump I wouldn't really give a monkeys what the general public around the world thinks - he got elected on a particular mandate and is merely dealing with the issues that he said he would to satisfy the American voters that put him there in the first place.
Like him or loathe him, but he is first dealing with domestic American issues like he said he would instead of pussy-footing around that politicians usually tend to do.
As for a state visit to Britain, then why not? Unless a country does something detrimental to our national well-being then I do not have an issue with any state visit with any foreign dignataries.
In fact being half Scottish he probably has more of a 'right' to come here than many others that currently reside within our borders.