All you need is some Vaseline and a mascara brush....
Basically, Vaseline locks in the nutrients or something like that (I'm not too sure...) in your eyelashes that helps them grow (this I do know). So, all you have to do is before going to bed dip a clean mascara brush into the Vaseline and put it on your eyelashes as if it were mascara, a lot of it! Then go to sleep! That's literally it. You can do it in the day but then you have like gloopy eyelashes and people will think you've got conjunctivitis or something. Where as using it at night it's gone by the morning.
the best thing is you can pretty mush get Vaseline anywhere, Tesco, Boots, Superdrug.... where ever!