A starting point, if you have not done so already, would be to establish your products H.S Commodity / Tariff code using the UK Trade Tariff:
I imagine your commodity code will be 8712 0070 99 or some variation:
After you have established this information you can refer to a leading trade procedures guide such as Tates or Croners and cross reference your goods against each individual requirement/consideration.
Nigeria runs a product conformity programme and it is likely Pre-Shipment Inspection of your consignment will be required along with a Certificate of Conformity. You may wish to email Estelle Mann (email@example.com) who looks after the Nigerian programme for Intertek, a leading inspection agency.
It is also likely you will require a Certified only European Community Certificate of Origin:
I hope this helps.