Can I use a proprietary cleaner on my machine?

I have a Hotpoint Aquarius Extra - about 6 years old an a splendid machine. I recently had to clear out the outlet pipe (chalky deposit more later on that) and thought whilst in a cleaning mood... So I went to our local Homebase(UK) and bought a Washing Machine Cleaner. On getting it home I read the instructions which say "For older machines you are advised to consult the manufacturer or your engineer to confirm suitability of this product". It contains 30% or more Oxygen based bleach agents; 15 to 30% Phosphates; less than 5% Non-Ionic surfacants and some smellies!
Anyone know if this is going to totally bugger my machine? Have I spent £1.50 and if I then use it have to pay out in excess of £300 for anew machine. We live in a hard water area.
Back to washing powders.. we have been told that they are OK in soft water areas, but not in hard water areas as they are made up of about 95% calcium carbonate (chalk) as a carrier for the actual cleaner as the cleaner is so strong it only needs a small amount, and the chalk just eventually exacerbates the hard water effect making the machine useless far before its actual sell-by date! Just though I would pass that on.