These days its difficult finding a parts catalogue for any car. Or workshop manuals . They seem to be restricted to the trade, who may pay an annual subscription for access to on-line data.
But the catalogues you list give a lot information, with beak down diagrams showing the Honda part number. If you enter the Honda part number into google it will often list suppliers of that genuine Honda part in the Uk or willing to ship to the UK. Prices including shipping may still be cheaper than buying direct from Honda yourself as a member of the public. It may include genuine Honda dealerships who specialise in mail order parts , such as Cox's or independent suppliers able to obtain Genuine Honda parts at trade prices.
Not an ideal situation, and you will also have to beware of LHD/RHD and specification differences.
