Being in the building industry and yet buying a Persimmon new home?
Didn't you read online what they are like, so bad they had to get an
independent review carried out which was damning.
To answer your question, yes the brickwork looks bad and yes if you have 35mm perp joints this is unacceptable.
But what can you do now? You have Exchanged and you either lose your 10% deposit or you buy this house.
Persimmon can tart it up a bit, cleaning the mess with brick acid, but this could mean your mortar is weakened and it falls out over the next 2 years. Try getting that sorted under the warranty!
Worse of all, your home is being built by a site manager that thinks this is acceptable "nothing wrong"
All you can do is write a letter to the Managing Director at Persimmon's regional office (or get your solicitor to write it - I hope you haven't also used a solicitor recommended by Persimmon!) informing them in no uncertain terms, you will not be legally completing on this house until you are 100% happy with the brickwork, that is, it is built to a reasonable standard.
Please expect more horrors when you see inside your "finished home" for the first time.
Please do get this house professional snagged and inspected before you legally complete!
Assuming you reserved after 4 October 2022, you can make use of the New Homes Ombudsman Service which will force Persimmon to sort out all the defects. You must complain to the NHOS before the end of the 2-year period after you legally complete. If you do, there are a lot of stages to get through before they will accept a complaint.