Hi Bob
You ultimately have to be guided by your own solicitors and barrister on this matter, anyone who says they can help would be misleading you. If your Barrister and solciitors have given you a figure which they feel is reasonable, trust them. If it is much higher than the offer made then wait and be guided by them. If it is within a few hundred pounds or so it is a decision for you to make. Take the money now or wait 6-8 months for just a couple of hundred pounds more.
However from what you have told me the offer is considerably less than counsel has advised, Proceedings would have had to have been issued by now also due to limitation so really you have to work out what exactly your losses were, in real terms not necesarily what you are claiming and see if the offer is reasonable taking into account the injury compensation also.
My advice, speak to your solicitors they will advise you accordingly.
I trust this helps.