So, in short, you haven't submitted a defence in time?
It depends whether judgment has been entered against you.
Usually these companies seek judgment pretty quickly as they are hoping people will fail on procedural points.
If judgment has been entered then you can apply to have it set aside but that will cost £225 and there are no guarantees as you do no really have grounds.
Also, for £225 you could probably all but pay the fine off.
And avoid the CCJ.
It depends on your priorities.
In fairness, the case of Beavis is in force now and the sum of their fines has been held to be acceptable so £25 was never going to be an adequate offer.
You can always rely on the adequacy of signs although the fact that there was adverse weather is not their problem and does not go to the adequacy of signs.
Can I clarify anything for you?
All the best.