For a start it is illegal to
insist that you must use the builder's choice of solicitor.
This is the worst thing you could do when buying a new home.
Reasons why buyers should NEVER use the housebuilders' choice of solicitor.Not only is it against the Consumer Protection Regulations (2008) it breaches requirement 2.5 of the house builder's own
Consumer Code for Home Builders. You should have been given a copy at Reservation. If not another breach (requirement 1.2)
There is no reason why you shouldn't be able to have your home independently inspected and snagged ahead of the CML inspection. I can recommend both Brickkickers or SnaggingInspcetions.
Perhaps Bovis are concerned that whilst the CML inspector may be persuaded to sign your home off as "finished", your own independent inspector will flag up many reasons why you should postpone legally completing.
I would cancel. The warning signs are there.
If you do go ahead, use your own solicitor. Bovis cannot sue you, it is your legal right. And most certainly, have the home independently inspected before you legally complete.