Can you park in a cul de sac

sort of... If it is signposted as 'nose to kerb' parking then yes you can park nose to kerb.
If it is not signposted with anything you must park parallel to the kerb in direction of traffic. Now don't ask me how you get parallel to a circle but apparently that's the rule. And I know as I and about 8 other residents just got TWO parking tickets for parking nose to kerb in an unmarked cul-de-sac.