I agree the testing delays are spannering this up for far too many people.
You ask what you should do - your whole household should (must!) stay home until you get result for DS2, or it is 14 days after his symptoms started.
You know this, but want a reason to believe you can wriggle round it.
You need wages, your employer is desperate to have you back. BUT what if you go back Monday and on Tuesday your DS2 gets his test result and it's positive? Then your employer has to go through track and trace of all the rest of his employees because you've broken the rules. Potentially have to close the whole site for 2 weeks if you are also positive (no symptoms) and spread it to other employees in the meantime.
Don't do it, it's not worth it.
People making the WRONG choices in situations like this is why it's still spreading so fast and stopping the hospitals from working properly again in hotspot areas.
Please don't let anyone leave the household until you get DS2 result back.
You're complaining to us, please let that be enough...it's shit that our test & trace system is so shit. You have everyone's sympathy on that.
But please don't give up and just become part of the problem! Hang in there, you can do it