Extension and build over agreement

Cakey01

We have had an extension built and are now in the position whereby we need a retrospective build over agreement from united utilities. It's retrospective basically because UU dragged their feet and dropped the ball when they were initially notified by the building Inspector and have, in a round about fashion, said they could have dealt with this better. 
Their legal team have sent us their agreement to sign (with a nice hefty legal fee) and their engineer advised us to get an indemnity policy once done. My question is do we need to get a solicitor to look over this agreement on our behalf before signing? I don't completely understand the jargon in the policy, but my husband seems to think because we will be looking to get an indemnity policy we should just sign. (I think hes just sick to death of the situation, it feels like forever and its been painful!)
Has anyone been in this situation and can offer any advice? 
Many thanks 

Yorkie1

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