It doesn't matter who you insure through you should always undertake thorough referencing of all applicants.
I found that the cover you are offered usually bears a direct resemblance to the premium. Cheap premiums = lower cover levels. I suggest you look at what Endsleigh offers, I use them because the cover appears to be better than most, especially when empty between lets for instance.
The advice I give should not be construed as a definitive answer, and is without prejudice or liability. You are advised to consult a specialist solicitor or other person of equal legal standing.