British English has many phrases that accept getting by without a perfect plan.
To muddle through: To succeed without a clear plan, by dealing with problems as they come.
To make do: To manage with what is available.
To wing it: To do something without preparation.
A bodge job: A rough repair that works well enough.
We’ll cross that bridge when we come to it: We will deal with that problem if it happens.
Suck it and see: Try it and find out whether it works.