I've recently discovered that labour in the building trade is expensive in the UK. For example, I paid £60 (East Midlands) to have three lengths of kick board fitted in my kitchen. The job took about 45 minutes. So the fairness or otherwise of what you paid is directly related to how long it took to do the work - and where you are located. Labour costs in London seem to be much higher than elsewhere.
With regard to your question about hinges - when I moved into my present home (28 years ago) it had a similar loft hatch to the one that you describe, with no hinges. I agree that this type of hatch is most inconvenient but you ought to have discussed the specification with the workman before he started the job.
However, if the job hasn't been done to a satisfactory standard (ie. the hatch doesn't fit properly) then you have a legal right under the Consumer Protection Act to ask the workman to make remedial works. If he refuses then you have recourse to the County Court. It's easy to file a claim online via the Claims Online website https://www.moneyclaim.gov.uk/web/mcol/welcome
It costs £25 to file a claim and this is recoverable from the other party.