The belt/tensioner is a piece of piss to do, I do every 3 years regardless personally, last one for a T reg 2L ghia, cost £54 inc 5 litres of oil, air filter, oil filter, from L&R in Norwich.
Defo change well before, belts deteriorate with age as much as mileage, and many have been known to snap well before due time/mileage, reminds me of vaux when they said 80,000 as a sales gimmick, soon swapped around to previous 40,000 after lots of breakages!!
I assume army ?, bung lad/reme a few quid.
tabetha