Are you saying that the third party is holding you liable for the cause of the crash?
If the other vehicle ran into the rear of you, then strict liability and the other party will be held 100% liable.
Take your solicitors advice. It is very unlikely that the case will actually get to trial as they (the third party) will become liable for increased and substantial costs, and so it will get them focused to come to an agreeable settlement sooner rather than later.
Whether the offer is reasonable or not, I cannnot say give that we don't know the severity or level of injury you sustained, but the fact that your solicitor is happy for it to at least go to trial suggests that he feels the claim is worth more.
Speak to him/her, have a chat and get their thoughts, they are after all the people handling your case and should give you an indication (if they have not already done so) as to what they feel your claim is worth.
Given strict liability against the other side, it is very unlikely that you will be worse off though.
