Cheers guys... actually the injector removal went fairly well (even though they've been in for nearly 160k miles). Only had a couple of hours free late afternoon, so didn't get much else done, other than drain the sump and then spill around 3 litres of filthy black oil all over the garage floor after accidentally kicking the catch pan... currently there's a whole bag of cat litter scattered over the mess.
Worst part was that one of the clamp bolts was seized and I snapped two T30 torx bits trying to remove it, the third one I found in the bottom of a neglected tool box was a better make and fortunately this one did the trick. I was worried about the bolt snapping, but it didn't. The clamp bolts are very close to the actual injector, which forces you to use tiny torx bits with a 1/4" drive (so not my much beefier snap-on ones that take a 3/8" drive).
I didn't soak the injectors overnight, mainly because I was busy last night and didn't have time to remove the engine cover, but also the injectors sit in a recess, so whatever you use for soaking will drain into the cylinders after injector removal (just seen your post Andrew, and I guess IPA would be OK in this regard). But I did very liberally spray Tesco's version of WD40 all around the injector bases and the clamp bolts (I know PlusGas is better, but wasn't sure if it would work and I'm too mean to waste it).
I loosened each clamp bolt, re-tightened, then started the already warm engine. I then loosened each clamp bolt in turn, only about half a turn, while watching to see if the injector had come loose. Thanks to the WD40, the resulting bubbling was very obvious and allowed me to very quickly move along the line before quickly switching the engine off... the injectors still appeared to be firmly in place at this point.
I then removed the small pipes (both ends) that go from the rail to the injector, unplugged the electrical connectors and removed the leak-back pipework, clearing the area around the injectors. Gently wiggling each injector in turn using mole grips allowed me to easily pull each free in a matter of seconds. Wrote the relevant location number on each part removed and then cleaned and stored all parts.
The copper seals were all in excellent condition and so there was practically no carbon build-up on any injectors... I believe this is how they came out so easily. It seems reasonable to ***ume that when the seal blows then the resulting leakage will deposit all manner of carbon and goo along the injector body and effectively glue them firmly in. So I was lucky, as this was the part I was most concerned about.
I've got a bit more spare time tomorrow, so will hopefully get to the chains then. Replacement (Febi) chains have been ordered from an eBay supplier (£81), but I'm going to buy the copper seals and a replacement oil chain tensioner from HH, and possibly other parts if they don't look reusable. I'm aiming to re-use the timing chain tensioner, as that one can be easily replaced after re-***embly if it's a bit noisy.