@LynneMarie you did the right thing checking before your trip.
It would have been a disaster if you needed to claim and then found out afterwards that you weren’t covered .
Have you tried the AA for house insurance ? It appears that they approve of having house sitters as long as they have public liability insurance (which THS provides with Standard and Premium membership )
House-sitting and home insurance | AA Insurance.
Please report back when you find a suitable company as it will help other members.