I haven't read the other thread but is it your solicitor saying you need the insurance and his saying that it is not necessary?
Honestly, just pay it, you won't even notice it, imagine the time and money you will waste if you pull out now, that would be serious cutting off your nose to spite your face if you pull out for £75 when having paid survey fees etc..
However, if this is actually a bit of an excuse to pull out because you are not really sure about the place....pull out.