Haynes recommend "standard is 80,000miles, but safer to half this to 40,000 miles."
Mine is due too
It is usual to replace water pump and idler pulley at the same time - as you get a new belt if either of these bits go in the next 7 years.
Also replace AUX belt at the same time, as it has to come off anyway.
If you go for a first change with all tensioners and pump, then an earlier change of belt only, you can get a longer run untill the next all-change.