This is just a basic guide to give you some idea, plot sizes vary greatly in different parts of the country.
An allotment plot is normally 10 poles. 10 poles are 302.5 square yards.
One pole is an area 5.5 yards’ x 5.5 yards. This gives 160 poles to one acre, which is 16 plots of ten poles each to the acre. More recently thought with the demand for allotments increasing and the fact that a full sized allotment plot can be too much for most people to take on, many councils have been dividing plots into halves and sometimes quarter plots.
Up until the 1908 Act allotment plots were normally 20 rods (or poles) and ranged from this one eighth of an acre to 4 acres in size (i.e. 640 rods/poles). The 1908 Act led to these smaller plot sizes to differentiate them from smallholdings.
With paths included it would be a tight squeeze to get 14 plots to an acre. A Main Path 5ft-10ft wide is normally provided, so that access to the plots may be had by people delivering manure etc. (if you have a grass path on your site, then use by cars etc. in wet weather is best prohibited to avoid ruts).
The simplest construction method for a brand new site is to plough the land and then roll or compact paths at the measured distances. These should be 2 feet wide between plots, and level, for Health and Safety reasons, and never encroached upon.