Sorry I cant answer your basic question , is the panel bolted or welded in place.
But by googling just the part number I found many sources for the part. One is a Russian site. I am not suggesting you buy from Russia ,if you even can , but the photo shows the part still installed in some major chassis rails. Compare this with the other photo of just the panel , on a Bulgarian site (It costs 193 lv -about £86 ) From this It looks like the panel may be spot welded in place to the side chassis rails, but I might be wrong.
https://izap24.by/tovar/10112525_panel-perednyaya-honda-jazz-2002-2008-60400saag42zz.htmlhttps://www.automega.bg/vehicles/honda-honda-jazz-2001-2008-01-08-front-panel-2005-049900225/Incidentally the panel is a lot cheaper in Bulgaria. Several sites, including in the uk , sell a pattern version made by Dietrichs for about half the price of a genuine Honda one. (Despite the Germanic name it may be made in China)
I have done similar jobs on rusty classic cars and even bolts are not always straightforward . They can seize and snap,requiring drilling out, re tapping etc .Or rip out captive threads which are themselves welded onto thin and possibly rusty panel work which then requires welded repairs anyway. But you might be lucky.
There does seem to be a lot of work involved dismantling the front end, radiators etc, possibly also having to regas aircon systems etc. If you can do this work, but not any welding or similar snags that may arise maybe investigate the availability and cost of bringing in a mobile welder to do only the minimum of work you are unable to do for yourself. Its possible that despite the amount of welding required in situ it may work out cheaper overall than the amount of dismantling required to replace the panel. If the main problem is just that fracture on your photo it might even be possible to drill holes and bolt a fabricated bridging plate across . It depends on the overall condition, and whether it is structural and might fail the MOT.
Sorry to say but I would also check for any other rust and other repairs that might be looming soon.
If all else fails what are your plans for a holiday this year ?

Bulgaria (and Romania) have a thriving industry in importing crash damaged cars,with many skilled repairers at labour rates a fraction of what it is in the UK. If you are able to organise it in advance, Maybe with the help of someone on a forum of local British Expats, you could maybe drive to Bulgaria or Romania , and Holiday there, (or Bus down to Greece) while the car is being repaired. Hotels and dining can be very cheap even in Greece if you go where the locals chose. . Just an Idea

Or if it proves necessary buy (or borrow/hire) a mig welder and learn to weld. You can reproduce spot welding by plug welding. You could get some of your money back by selling it again afterwards.