Urgent tyre help, drive or put spare on?

33psi is a bit low for front tyres for our cars, but you will be OK at 32psi for a short journey. Certainly safer than a space saver, those things are dangerous!

A space saver should never be used on the front

umm...space saver in back and back tire in front and buy two new tires

if you're saying you have 3 at 33psi and one at 32 psi cos it wont go above, drop the other one across the axle to 32 so it matches, it'll be absolutely perfectly safe to drive home on, if you feel anything unusual in the way its driving, stop at another petrol station to see if any have lost air drastically or not

loss in pressure so much on one wheel could be a crack in the alloy, a leak in the seal (usually on the beading), an issue with the valve or maybe a slow puncture

a space saver isn't dangerous at all, they're purposely speed restricted and are designed literally just to get you home or to a garage, and on a front wheel drive/4 wheel drive, should only ever go on the back, by putting the rear alloy on the front if its the front that's flat, providing you don't have wider rears, although I often see many cars, mostly taxis, with space savers that have been used for days on end, because as we all know, taxis operate above the law