Forget CO-2 cartridges ... too expensive and requires a bit of technique to make them work. Stove? Really? Don't burn down your Hostel room!

A simple decent quality bicycle pump will work fine. Remember: On your Tornado 250 you really don't need more than about 15 PSI to proceed. Of course, stop and "air up" at first opportunity (tire shop, taller, Gasolina) ... and if riding at 15 PSI, keep speeds to 50 mph or less.

I'm guessing Honda recommends something like 20 to 22 psi front / 23 to 25 PSI rear, am I close here? Any auto parts store will sell a pencil type air pressure gauge. Do you not drive in the UK? This is so basic.

On a lightweight 250 you can easily ride safely below those stated pressures ... so you really don't have to be pumping your bike pump all day long. Getting the rear tire up to 15 to 18 PSI will suffice until you can get to a "real" compressor. Don't worry about seating the bead. Just get some air in there and go ... go easy in the corners.

Tire Irons:
I like 3 Irons but you can make 2 work if your technique is good. Get a third if you can. If you get a flat, just ride it.
Keep going. In a few miles you'll get used to riding it flat. Don't crash but it will move around until you figure out how to do it. Ride to help unless you're really middle of nowhere. Riding flat will RUIN the tube ... but beats changing a tire!
You decide ... I always ride ... and it's why I carry 3 spare tubes.

You really need your Valet with you to deal with all these minor issues.