If your search eBay for 'Honda ctdi timing kit' the top result is a Holdcroft Honda kit of parts for £629... comprises both chains, both tensioners, both tensioner arms, guides and injector seals. But might be worth contacting HH directly and seeing if the usual TA discount will apply?
I got Febi chains from eBay and - after careful inspection - only also replaced the oil pump chain tensioner, timing chain tensioner arm, injector seals and the tensioner bolts (all from HH)... total cost was around £300 (half of which was the tensioner!). You don't need any special tools to do the job, but the locking tool for the crank pulley is useful. But I guess if you get a garage to do the work they'll have one?
There's a fair bit of labour involved, so be prepared for a large bill!