My service handbook says every 1000 miles, but I've seen a website suggest every 4 or 5 years.

It's a 2009 Polo Bluemotion (1.4 TDI) the 05-09 model and it's done 57000 miles now.

If it does need one am I ok to just hold on till the next service in 5 or so months at roughly 64000 ?

I'm massively in favour of extra servicing, but that is way OTT!!!

As the car is around the five year old mark, it should have the belt, tensioner and any idler rollers replaced for piece of mind. It's good practise / sense to get the coolant pump replaced too as it's not just the belt that deteriorates with age / mileage.

Even though the car hasn't covered the recommended mileage, it has reached the time limit for scheduled replacement and the £300 ish cost for replacement is a lot less than an engine rebuild or exchange engine if the worst happens and something on the timing side goes !