Hi Graham, sorry to hear you are not feeling well. I would certainly say stay away from lemsip or beachams hot drinks, they are sugar based. I normally have paracetamol and an antihistamine if I have sneezes or runny nose. Strepsils do a sugar free version. Don't be tempted to overload on carbs (Before I found this forum and understood the need to low carb, I did that an passed out in a cold/carb type coma for a few hours and was really poorly for a couple of weeks).
Top tips, rest and drink plenty of fluids, try making homemade chicken soup, have plenty, it has some special quality which makes you well. Take a multivitamin. Make sure you eat little and often as being unwell generally can play havoc with your BGs.