I’m not fully on-board with the saying “There is no such thing as bad weather, there is only bad clothing choice” as there is weather which I wouldn’t train in. However, in the main I am of the opinion that you can train through most of what the British weather throws at you, provided you spend some money on good quality, well chosen training kit. In addition, you can’t for example, only train for a marathon in good weather as what then happens if on race day it is raining? Firstly, you are likely not to enjoy the race, which is after all why you do sport. Secondly, and one of the possible reasons for not enjoying the race, is that you will be running in the wrong clothing. An example of this is a man wearing a cotton shirt and in the wet the cotton shirt becomes very heavy and if the man has not put any protection over his nipples at the end of a marathon he will have extremely bloody nipples. The answer would be to use a shirt made from a technical fabric which wicks away moisture and the “belt and braces” protection would be to use either tape or a specific product called “nip guards”.
The result of all this preparation is a much better chance of finishing your race with a smile on your face and possibly a personal best!