Sorry to hear about your prang

This reply might be a bit contraversial. Apologies now. My experience of insurance companies is not entirely positive, and the following is based on my own experience and as such is my own opinion. Other people will pick the useful bits from the not so useful. :-/
If you only have TPFT cover get the car recovered somewhere safe ie not where the insurers have taken it. You still own it, you can say where it is taken to.
If they write it off, you'll never see it again and they'll bump up your premiums, leaving you well out of pocket. If you DON'T claim, you CAN'T lose your no claim bonus.
Get someone knowledgeable to look the car over. If readily repairable, the bits are easy enough to come by, if not it can be broken to good effect, and the cash can be put to another car.
If the rear side windows in the boot are intact and the tailgate(regardless of condition) still opens and closes, then the back end might be ok. If the front doors open without catching the wings and the slam panel is straight and level then the front end might be ok too. The crash bars behind the bumpers can take quite substantial knocks.
Hitting a deer at 60mph cost me a bonnet and headlight. The Insignia that made my car a cat c write off folded up like a tin can. mine needed a wing, tailgate, rear wing, a few other bits and pieces and four days labour.
The Omega is a tough beast. The chap who repaired mine, (was ford apprenticeship trained), reckoned that it was stronger built than the mk2 Granadas that he was trained on in the early eighties.
Don't rush your decision, and take it easy for a couple of days.
Al.
