I will do that in the future, olduser1. To be honest I just went with the "convenience" option this time which is probably not the most economical thing to do.
Thanks, culzean. I will take advantage of your advice and mark the bolts.
I do not hear any "wrong" or unfamiliar noise from the engine. I read somewhere on the forums that for a 2003 Jazz it is recommended to have the valve clearances adjusted every 25000 miles. Without knowing I've looked into it the dealer provided me with the same information. Since my car came with 1 month old service history (alternator belt + cvt flush), I decided to go with the safe option and change every essential consumable so I can start tracking the wear and tear and avoid getting stranded in the middle of a foreign country (I'm planning a trip abroad soon).
In addition, I'm hoping to address my 29 mpg city fuel consumption with the tappets adjustment. I called a few Honda dealers and they quoted £100 for that service.