Nordic and Pictish are too young for TMA really, it only includes prehistoric sites. The cut-off for British sites* is when the Romans arrived, which is obviously problematic in Scotland, where they didn't :)

Basically you're fine with Iron Age and we've certainly nudged into Romano-British a few times (Chysauster is an example of the latter).

*The cut-off for the Med etc would be much earlier of course.