ur looking at roughly I'd say at least £1.5k to repair that mate. Labour alone will be the biggest hit but I can tell u that for a full front panel ur looking at £173inc VAT IIRC. For a bonnet, roughly £100-150 used. Wings, £50-£80 each used. Bumper, £70 used....As you can see thats only a few of the parts and the price is mounting up. Once u add spraying and then labour rates for jig work etc it'll be quite a lot.
just out of interest tho mate, what year is ur car and what mileage has it done? the valuation u've been given seems quite low but I think it'll be easier and less hassle to just take the money and get a newer/better one.
i know some people will probably think that what am i on about coz i got a light damaged car as a project then got it repaired but my one had stupidly low mileage and less damage than urs but also had a higher residual value so taking thinks like age mileage and residual value into account and especially as the insurance only valued urs at £3.5k I'd say take the money mate.
Hope everything gets sorted one way or another tho.