I teach in a state secondary school in the UK and wear an ffp3 the entire time indoors. I also have hepas in my teaching room & the only window permanently open

There's the norizite spray by Birmingham bio - couldn't say how similar it is but worth looking at.

Smitten kitchen's courgette or cauliflower quesedillas. Sausage, gnocchi, tomatoes & broccoli from Cook with Gem website, or tomato mozarella gnocchi from Roasting Tin (or just chuck in oven for 30 mins gas mark 5). Halloumi burgers. Sweet potato black bean chilli for more veggie options.