help with water pump

HI All, i have a lunar solar 525 (1999) and over the weekend my water pump stopped working. how do i check if its the pump or something internal  in my van?? the pump light was on...but no water coming out all other electric is working fine...

or how do i know which pump to buy if i need a new one>>>are fittings different?? I'm on holiday in just over a week so need to sort it out if i can asap.