firstly all the writings about FAR 25 and performance A is not relevant to this poster's query as everyone here knows just how completely diffrent the certification criteria are.
I don't know about there in the UK, but here in the US under the FARs the pilot in command is directly responsible for and is the sole authority as to those sorts of decisions...but if you make that decision,...may have other consequences, for example, to wait forever and burn lots of fuel etc. perhaps upset a few folks, get laughed at, derisive comments --all to be ignored once you've made your decision but the decision shouldn't be made in an ignorant manner...e.g.
but in a SE or far 23 twin you have to evaluate the two options if the surrounding terrain is unfriendly,... it may be worth the wait,...if however you have a 10000' RWY at a busy class B terminal then perhaps the wait is not worth it
PA