I wonder if someone can help me out... We are a small engineering company using a few pieces of lifting equipment. We have these tested in accordance with LOLER every 6 months. Equipment includes slings, hooks, plate grabs, overhead crane and our lorry mounted crane. The costs to have these tested is becoming a little expensive in my opinion. I wonder if someone might know whether we can test this equipment ourselves, and if so what training/insurances we would need to do so. Thank you in advance for any information provided.

Slings & hooks fall under accessories and therefore i believe sit within 6 monthly inspections under Loler.

This is the really important part. As a "small" company you are very unlikely to be able to get a truly independent person (independent form the operation, independent to line management etc.) to undertake the statutory inspections. To answer your question, no you shouldn't inspect yourself. But as others have said, you can adjust the frequency for some of those items.