Ok, @McKenzieFriend001 - Radishes, sow them directly in the place they will grow. They don’t want to be transplanted. If you don’t have a veg patch, sow the seeds in a trough or planter. They can be outside now, no cover needed. Water the trough first, then sow the seeds in the damp soil. They germinate quickly.
Tomatoes - start them inside in your propagator on a windowsill. Water them from below I.e. pour water into the propagator and let the soil in the pots absorb it as needed. Once they’ve grown their first “true” leaves (not the seed leaves) you can pot them on individually and put them in your mini greenhouse.
Red Peppers - these usually need heat to germinate well. I have a plug-in propagator on a windowsill that keeps it around 18 degrees for peppers, chillis, aubergines etc.
As a new veg gardener, choosing things that grow well in this country will give you a better success rate than Mediterranean vegetables. (Courgettes are an exception, they grow so well here, unlike peppers and aubergines)
Think salads, peas, beans, herbs, cucumbers, squash and yes, radishes and tomatoes - rocket will germinate in under 10 days and will give you a boost in confidence.