I rang the Immunistaion officer at the council, who said its good to have the immunistaion in the first three days, but within 5 dayss of exposure (which is today) can be OK.

So I've booked him in for 3pm today, my poor mum, she's going to have to take him

I hate getting immunistaion in the afternoon, we always go in the morning to observe.

Thanks everyone for your thoughts & advice.