If you have noticed a leak from your soil pipe then then you could have a blockage in the pipe or in the main drain. There could also be a broken seal on the pipe, if a seal is broken that can let toxic smells out and should be dealt with as soon as possible.
If the water in your toilet is rising then you have a blocked toilet. There could just be a blockage in the pipe or there could be a larger blockage in the manhole (Inspection Chamber) - Good to know, of the water is also low in the bottom of the toilet then you could also be experiencing a blockage.
If your toilet is overflowing then you need call a plumber or drain company immediately as you have a serious blockage in the main drain. Mansfield, Nottingham