That mileage is getting into fuel injector failure range. If it spins over fast it's not the starter dying. So it's most likely injectors or glow plugs. Tomorrow morning when it's cold and shitty when you leave for work, turn the key, wait for the glow plug light to go out, count to 15, turn the key back to off, do that twice more so you've cycled the plug warm up 3 times. Then try to start the car. If it still moans about starting you need to have a friend/garage perform a leak off test on your injectors. If it starts ok then repeat the process for the next week or so and if its 100% fine change the plugs and you should be ok.