That is a big repair. No, your insurance cannot restrict you carrying out work on your own car whilst it is in having work done. However, you cannot try to claim for unrelated damages as part of your insurance claim (and it is to this that the statement is being made). The best thing to do is contact your insurer and make them aware that the vehicle WILL be having work done at the same time. Should they be insistent, raise a complaint and advise they are breaching "unfair terms and conditions in a contract regulations" which is also a Financial Conduct Authority regulation: www.handbook.fca.org.uk/handbook/UNFCOG/1/?view=ch...r