I developed flu like symptoms on Wednesday evening and didn't get any sleep that night with aching muscles, high temperature, sore throat and headache. So I phoned in sick yesterday (Thursday). I seem to have made a speedy recovery, just left with the sore throat.
I'm wondering whether I should go in to work today? Physically I could cope with it but would I still be infectious and potentially pass it on to colleagues? I also work with the public including the elderly.

I would say you were definitely still infectious, and in your line of work you definitely can't afford to pass the virus on. I would consult a doctor (even if it is just a telephone consultation) to ask them what they think.

Hi
best stay away till monday, then you will be sure not to have it.
if it was flu and your body dealt with it then fine but you could be infectious.