Hi Keith,
There is no right or wrong answer to this. A lot depends on where you are and the type of land, whether clayey, sandy, or on chalkland it will all be different types of grass. At this time of year difficult to tell as well, better in a month's time when the grass is fully underway. Generally look out for the condition though, how much weed there is present such as nettles, docks etc. A lot of weed is not good but at the same time probably indicates that plants grow well. If it is light land it will likely burn up partially in the summer and so there may be thin patches on the tops of small rises with better grass in the hollows, by contrast heavy land may be holding water in the hollows with better grass on the small rises.
If you get a field and it is poor then it can be plough and resown, which although a cost will give piece of mind for the future and you can get the appropriate grass seed for the ground conditions.
Daniel