Car accident and whiplash claims

Hi just looking for some advice on a car accident I had last month. I was stationary in traffic at a roundabout waiting to turn left. The car in front of me went to go however they didn't. I then went into the back of them as I was concentrating looking right for oncoming traffic and hadn't seen that they didn't go. Now I couldnt have been doing more than 5mph as I was stationary at the time and only moved forward the space left between the 2 cars (2ft or so). NO damage to either car. Well mine had a minor scuff on it that rubbed off but that was all.
The other driver has now put in a claim to my insurance company claiming WHIPLASH!! Was wondering if this has happened to anyone else and what the outcome was? Also do I have my to pay my insurance excess if the claim is upheld?
Thankfully I have protected no claims.

Any advice gratefully received