You're flying circuits and you just turned downwind, ready to give your downwind call, but you can't get a word in as the radio (tower) is really busy. Before you know it, you're ready to turn final and still can't get talking to ATC.
Do you continue with your approach? Potentially without permission to land/Touch and Go? Or do you abort and go around? At which point should you have made the decision to go around due to no contact with ATC?
I would continue to the flare and go around then if I hadn't had a landing clearance. At Cambridge if you can't get a word in it's usual for ATC to call you with "clear land" even though you haven't got a "final" call in.