Dutton Kit Cars and their owners
Are you jacking on the axle or on the chassis because it looks like the damper and coil spring are taking the car's weight? You need to jack it on the chassis and not on any part of the suspension or axle. When the chassis is jacked up then the axle should drop a bit and the angle of the strut will be a little less extreme. Then you might be able to hammer it out. To hammer it out then I'd refit the nut to the bolt to protect the thread. Once the bolt is driven as far as it will go with the nut on the end of it, then you can remove the nut and it might work its way out if you unscrew it as the thread will grip against the bush.
You might need to open out the hole in the suspension at the threaded end of the bolt when you reassemble it, otherwise the new bush might not last long and it could be a pig to fit.
Jack on the diff, axle stands under the chassis, release the jack. allow axle to drop.
Hacksaw through bolt (the hard part) either inside the suspension arm or outside, either way it'll be a pain. Once the shock is clear you should be able to change the bush.
Re-assembly however will be a bigger problem as james said - the bush and arm do not align and it will be a pain to get a new bolt in. Either straighten the arm or re-drill, washer and weld.
You do need to get the car's weight off the bolt before you undo it. The spring compressor is not doing anything for you, as far as I can tell. (Normally you would use a spring compressor to allow you to remove the spring from the damper). It would be better to let the axle hang from the spring because that will improve the geometry, making the strut slightly closer to vertical.
bit of heat, push with index finger, jobs a good 'un :-)