Please Help! Urgent!

Hello, please can someone offer some advice.

I have a ford fiesta. Yestrday a rattling sound started to come from the timing belt area. Sounds like gravel in a washing machine. It does not increase when revved.

I often have to fill up the water tank, so could the noise be from the water pump?

If it is the bearings in the water pump that have gone is it ok to drive tomorrow as I need it for work. It is being seen by a mechanic in the evening.

So I just want to know if I can use it for the day.

Thanks