Definitely visit your local sites, check them out as regards plots that look neglected. Try to pick a time when there are people about (weekends are good) and get chatting. Explain that you really want an allotment. If there are neglected plots you may be able to take one of them over as Seahorse did cos the managers won't advertise it unless it's clear. You may also find that someone has taken on a plot and can't really manage all of it and would be willing to share. Personal contact is definitely the way to go, rather than council waiting lists. Works even better if you have a good site representative.