Freelander 1.8XE Timing Belt

My 1999 Freelander has now reached 48,000 miles,
I have heard that the timing belt needs changed at that mileage and as I
don't have a manual yet, is that correct and is it a complicated job ?

I have done one several years ago on an Astra OK but wondered if I might be
better getting someone to do it for me?

Thanks for your help