Folks, apologies for the late reply! I did end up replacing the chain and tensioner last Friday however with the adjuster bolt being very tight (had to use a breaker bar), the timing tool I bought bent both pins (cheap tool, buy a decent one!), so I had to get a lend of another timing tool as the original wouldn't time up the cams correctly (I was unfortunately off a tooth on the intake cam the first time round).
That being said, it's now sorted and sounds fantastic when warmed up! Only noise now is the tick from the injectors.
If you are planning to do this yourself, buy a decent timing tool. I would reccomend the Laser set:
http://www.ebay.co.uk/itm/Engine-Timing-Tool-FITS-AUDI-A3-A4-A6-S3-TT-2-0-2003-2010-T10115-T10252-T20018-/181012915733?hash=item2a2535e615:m:mrCRB1yDqj-pZdNiQrqNHQAThis is the T40080 polydrive you'll need too:
http://www.ebay.co.uk/itm/271959949245?_trksid=p2060353.m2749.l2649&ssPageName=STRK%3AMEBIDX%3AITTop tip when removing the adjuster to avoid stripping the head, have a second pair of hands put pressure on the socket while pulling with a breaker bar. Also, give the breaker short heavy bursts of pressure to break the seal.
I didn't have time to take many photos to make a guide but found this one after replacing the chain!
Removal guide:
http://workshop-manuals.com/volkswagen/golf-mk5/power_unit/4-cylinder_injection_engine_(2.0_l_engine_direct_injection)/engine_cylinder_head_valve_gear/valve_gear/removing_and_installing_camshaft_adjuster/removing_camshaft_adjuster/Replacing guide:
http://workshop-manuals.com/volkswagen/golf-mk5/power_unit/4-cylinder_injection_engine_(2.0_l_engine_direct_injection)/engine_cylinder_head_valve_gear/valve_gear/removing_and_installing_camshaft_adjuster/installing_camshaft_adjuster/Providing you don't need to drill out the adjuster bolt (which you shouldn't as long as you're careful) then the chances of needing to replace your adjuster are VERY slim as it is not the cause of the noise and are unlikely to fail as long as the car has been maintained with quality oil in it's lifetime. If you do need to put a drill on it, do not chance re-using the adjuster, replace it.
Parts you will need to replace, part number and priced by TPS including VAT:
Cam chain - 06D109229B - £52.65
Cam chain tensioner -06F109217A - £75.85
Cam cover gasket -06D103121B - £4.77
Fuel Pump o-ring - 06E127248 - £7.20 (optional but recommended after having fuel pump out)
Valve cover gasket - 06F103483D - £19.89
Exhaust cam adjuster bolt -06D109281D £2.56
And if you REALLY want to replace the adjuster at the same time...
Cam chain adjuster - 06F109088J £321.72
Labour wise, you are talking 1-2 hours for removal and 1 hour to refit, it's not difficult.
@Peskyjones @JamieBiz @dom069 @Reflex ^^ Get it done, better safe than sorry. That is definitely cam chain rattle in your video.