The Royal Horticultural Society is a source of much knowledge and information in the world of horticulture. Their free advice section is full of useful knowledge on growing. Much as they would like you to join and have many ways to try and part you from your money, much information is provided free.
The Allotment and Gardens website is full of growing advice from month by month guides to videos, recipes, a chat and help forum and also a chicken and poultry section. There’s a monthly newsletter which you can sign up to which comes with offers and information.
Prudhoe Gardeners’ Association is a member of the National Allotment Society which has advice for allotment holders. This is a much more limited advice area as it is strictly for allotments but there is valuable information to be found there.
These sites are provided by people with a wide variety of information available, time and staff to present the information and the ability to keep up with changes in the legislation regarding such things as chemicals where there have been many changes in recent years.