how useful are fetal Dopplers?

Jade

I'm just wondering who has a fetal Doppler and how easy are they to use especially in late pregnancy? (37 weeks today) I had a fall bumping my belly 2 days ago. Me and baby are both fine, spent the night in hospital being checked over but I panic every time she doesn't move for long periods of time. I'm wondering if getting a Doppler will help reassure everything is fine, but I don't want to get one if it can be hard to find the heartbeat and I'm just going to panic myself even more. Any advise would be appreciated xx