Grass left over winter will simply die back and become a tangled mat which will be very difficult to contend with in the following spring. However, it can be eaten down in the autumn and if your fencing is adequate; it might be best to have someone stock it with suckler cows or store cattle. If the field is wet don't over-stock it. Cattle can make a sad mess of ground in wet conditions. Someone might be interested in cutting and round baling - it is still early enough for that. I suppose the field size might have a bearing on its commercial attraction but I am sure that some one local could reach an agreement with you?