Hi Shortie!
Would love to help, as we got our plot 2 days after first deciding we wanted one, but as it was just before allotments and GYOing took off and became sooo popular and trendy, then I'm not sure we count!
Basically, we looked up details of where they were on the net, emailed the council liason, then went to the plot twice in 2 days on a weekend, hoping to catch someone that could tell us if there were any free, and which ones they were. The second trip we hit the jackpot, met the council liason and took the plot we were offered immediately, literally starting to clear it within 20 mins of getting the plot! After 3 months of double digging over the winter we were offered a 2nd half plot, which we took, and at the end of last year we approached the council liason and asked to go onto the waiting list for a second full plot adjacent to our first full plot, (with the understanding we would give up our half plot if we got a second full plot), fortunately, the plot we wanted came vacant 8 weeks ago, and we've now completely cleared and planted it up!
Hope thats of some help!