From that picture mandg it doesn't look too bad although the only bit that is a bit "worrying" is the mark at the top of the wheel arch but then you say it's not dented so it shouldn't be a difficult repair.
You'd be surprised though at how much it could cost tbh.
The bumper would need spraying probably around 1/3rd of the way round to blow it in properly. If it needs spraying on the wheel arch (which it looks like it will) then it will need blowing in higher up the rear quarter & could need spraying fairly high up (possibly even up to the roof line) with the lacquer in order to do a decent job. Might be easier if it wasn't a black car.
Prices do vary massively so it is always best to get as many quotes as possible and to whenever possible use a bodyshop that either you or someone you trust has had work done there previously so you know they do good work.
I'd say him saying £350 to have the work done locally is completely believable to me although I'd say it could maybe be done a little cheaper.
As you say his car isn't taxed though then this makes me think s*d the guy!. I mean we all pay our hard earned money to run our vehicles and follow all the rules as best we can.
Either go to the Police or ring your insurers possibly.
Whatever you do though try to make sure you don't let it get to you. You need to stay calm and relaxed as much as possibly whilst your pregnant as the most important thing here is you & your unborn child.
