Some sources for guidelines and data sets.
These are search engines which will search for research datasets which have been published. Of the list, only Elsevier DataSearch will find data that has been published as supplementary material. Just as with general internet search engines, there is not one which will find all the datasets so you may have to search across multiple sources.
Primary care prescribing data is captured by the NHS reimbursement agency, the NHSBSA, from the NHS prescription forms dispensed by community pharmacists across England. As the patients' names and the conditions for which medicines are prescribed are not required for the reimbursement process this information is not available at a national level. It is possible to estimate the number of patients receiving a particular medicine but the accuracy of the estimate will depend on the range of dosing patterns and the number of clinical indications for the medicine.