If you are still looking to have the work done, I would recommend using genuine GM kits as aftermarket parts are just not reliable and some members here have found themselves having to do the job again.
Genuine part numbers for the Z22YH (Direct):
Camshaft Timing Chain Kit - 55569838 (This is the latest spec kit which includes the Z20NET timing chain tensioner)
Available here
Balance Chain Kit - 55563405
Available here
It's also a good idea to renew the front crankshaft oil seal which is seated in the water/oil pump/timing cover, as they tend to leak once disturbed. (part # - 55564509)
A new gasket is sometimes required for the cover but they can usually be reused (part # - 24435052)
...and an oil and filter change is prudent at the same time.
Not sure where you are located in the UK but I would thoroughly recommend @[deleted] (based near Telford) as he has carried out timing and balance chain work for numerous members on this forum. He knows these engines thoroughly and will look after you. It's probably best to contact him via the forum using PM (conversation utility) for costs, but you'll be pleasantly surprised as he is very reasonable if you are willing to travel.
Hope this helps. 🙂