With respect, your solicitor does not have the expertise to determine whether or not the snagging issues are merely aesthetic. He or she should have the expertise to determine whether you will have to pay interest if you do not now complete.
I would suggest that you (a) contact your architect and ask their views on whether there structural or systemic problems which need to be dealt with. If there are non "aesthetic" issues, I would hold out if possible, and consult your solicitor on the terms of the contract - a day's notice to complete sounds as if someone's messed up somewhere along the line. If there are no items of major concern, or if you are locked into completing today, then (b) ask your solicitor to obtain an undertaking from the builders that all outstanding snag items will be dealt with, as a condition of completing the sale.
... has this been rendered moot by occurrences during the day?! Hope all has gone well, if so!