Single Farm Payment you have to farm more than 3ha of eligible land, plus you have to hold entitlements, submit a Single Application Form, maintain your land in Good Agricultural and Environmental Condition (GAEC) and meet a number of Statutory Management Requirements (SMRs) covering the environmnet, food safety, animal and plant health and animal welfare(Cross Compliance), keep comprehensive, accurate and up-to-date records.
I haven't been brave enough to tackle GAEC and SMRs yet.