You have a problem then - walking on it isn't good, as it will compact it, but the only thing that might help a bit is spiking it with a garden fork - a long job depending on how much lawn you've got. There are also machines that do the job - I believe you can hire them.

I really think it would be better to leave well alone and hope the rain stops.

If it is always marshy you may have to accept that this is not the spot for a lawn either that or put land drains in.

If it is boggy in places, then the earth is compressed. I would try to for all over, as suggested, and literally lifting the earth where very boggy. It makes a satisfying slurp sound.

If that does not help then lift the grass that bogs down, improve the soil by adding mulch (bark chips work well) and a some builders sand (thicker than play sand) and fork it in. Then rely the cut off grass strips. That will help and the grass will look fine by spring.

thanks for your answers.
i have only recently bought the house (july) i dont know how long the lawn had been left for but the grass was quite high(4-5 inches) we have had alot of rain recently so im thinking its just the amount of rain we are having.

again thanks for your input .