What a nightmare for you, quarantine is 6 months, unless the chip can be scanned.

Did you have the chip read before you left the UK ?
I know when mine went for their passports I found out my rescue girl had a chip but it didn't register when scanned by the rescue centre that she came from

It might be worth trying to find out what make of scanner was used when the chip was registered so then you might be able to get your dog re-scanned and out of quarantine.