Employer threatening my probation if I don't drag myself in when I can barely get out of bed.

I live in Northern Ireland and have a hybrid-working job. I've been employed here for just under 1 year and 9 months (9 months on a temporary contract and coming up to 1 year on a full-time contract).

The rule was always if you are sick you work from home but I've recently caught this bad flu that's going around and the muscle aches its giving me are so bad that I am struggling to even walk around the house. My line manager called me yesterday to say that senior management is kicking off and I'm being accused of breaching the hybrid working policy for not coming in 2 days this week despite the fact they know I am sick and I have been communicating that with them.

The bit I am most concerned about is that they directly threatened that I may not pass my probation because of it despite the fact that the only other time I didn't do my 2 days was when I was coming back from a week off on leave and no one told me they changed team meeting to the Monday which resulted in me missing it.

I've joined the union and have been told they will contact me ASAP but I just want advice as to what route to take because I spent a couple of hours last night reading the policies they say I'm in breach of and nowhere in them does it say that sick staff have to drag themselves into the office and it really doesn't make sense from a health & safety standpoint considering all that will do is put my own health at further risk and threaten the health of anyone around me in the office.