It looks as though the female is now incubating the eggs which is a fair indication she will not lay anymore. The maximum that we’ve definitely seen is 10.
She started to spend more time in the box from yesterday, 5th May, so we reckon incubation has started. Blue tit eggs take around 12-16 days to hatch so anytime from Thursday 17th (ish) onwards.
Update 7th May: Yes, definitely staying in the box now and the male has started to bring her food – a good sign of an attentive male partner!.
Keep a look out!