It's not the end of it, but weather is an "extraordinary circumstance" which would bounce you out of EC 261/2004 compensation. Whether three hours is a reasonable time for KL to scramble a new aircraft and crew at AMS, its worldwide hub, is a different question.

In a court proceeding, it would be for KL to prove this.

If you are located in the Scotland, you could file an action through Scotland's version of MCOL. All online. If the process fails, you would then wind up in court. Hearings may be telephonic.

At this point, best to follow the forms for a letter before action so that, if KL does not pay up, you may proceed directly. Or, if you don't care that much, drop it.