I'm new to this forum but I am a keen sailor and therefore weather has always been on the top of my agenda.
First, it depends from the latitude. The more away from the equator you are, the more time to catch a sunrise/sunset you have. In tropical areas, it lasts for seconds, literally.
Second, changes of weather are more interesting for sunset/sunrise photography than overcast/sunny weather, especially the time after rain, when the air is "cleaner".
Having said that, and now this is my opinion, sunrises are better with the bad weather incoming. This is due to the higher level of humidity in the air at horizon, still not present where you are shooting, and gives the red/golden colours to the sunrise.
Sunsets are the opposite - after the rain the air is much clearer and the effect nicer in photographs.
I do not live in the UK so am not familiar with the best weather forecast websites, but if you have a friend who is also a sailor he will for sure be able to point you to a website with a computer simulation of the next three days in 6 hours intervals. Longer forecasts are not that reliable, so I suggest you plan the sunrise/sunset shootings max two days in advance. If you plan to really get into forecasts, clouds are a good telltale, but knowing to read the sky takes a lot of time.