As a new-bee I applaud your view on safety and your concern for the hospital's helipad. You have won my admiration.
I am also routinely flying about 1/2 mile from a hospital helipad. There are some general behaviors of the in-bound helicopters that can help you to avoid being in their flight path or airspace. Most helicopters will fly at a pretty good altitude (above 500 ft.) in a circle around the helipad to check that it is clear for them to land. You often will hear and see them. Next, their landing flight path will be low and slow and most importantly into the wind. Knowing the direction of the wind at the helipad (a 1/2 mile away) will allow you to know their most probable approach where they will be below 400 ft. The quick test is if you face toward the hospital, if the wind is blowing at you, the helicopters will make their approach directly overhead. This is when you will need to be most concerned and vigilant.
I am also routinely flying about 1/2 mile from a hospital helipad. There are some general behaviors of the in-bound helicopters that can help you to avoid being in their flight path or airspace. Most helicopters will fly at a pretty good altitude (above 500 ft.) in a circle around the helipad to check that it is clear for them to land. You often will hear and see them. Next, their landing flight path will be low and slow and most importantly into the wind. Knowing the direction of the wind at the helipad (a 1/2 mile away) will allow you to know their most probable approach where they will be below 400 ft. The quick test is if you face toward the hospital, if the wind is blowing at you, the helicopters will make their approach directly overhead. This is when you will need to be most concerned and vigilant.