I bought it as pedalheaven (my local bike shop) was closed and as I have a race tomorrow.
I will return it if doesn’t fit.
Yes it can but the slightly overstretching of the tube can increase your risks of puncturing.
Tubes marked with the same size as the tire are always slightly smaller than it and stretches upon inflation, so I always suggest going for an inner tube with its width size one step or level higher than the tire so that it won't have to stretch as far to conform to the tire's size, possibly making it more resistant to flats.
Should be fine, I have heard it said at a push you can even get a 26 tube to work on a 29 wheel. On a side note, as you are entering a race you must be pretty into your riding. I can not overstate the benefit of going tubeless. No more punctures. Tubeless is not immune to getting a flat, but in comparison it is rare. I have been running tubeless for over 3yrs, no punctures ever. If you are racing, you might be in the lead, one puncture could see you coming last.