"to land with a leak raises the hazard...". Ah well, best to just keep flying around until it's all gone then!
Ha! A perfect example of droll Brit humor.
Back when I was flying tactical stuff, almost all of it had a single feed tank to the engine/engines and if you had a leak from downstream of the feedtank, you had better get it on the ground before the go juice ran out unless you could safely isolate the leak.
Transport aircraft fuel systems are a bit more redundant with separate feed tanks for each engine. (No doubt exceptions exist). As long as the crossfeed remains closed and you have enough fuel to make it to a suitable airport, do you really need to land ASAP?