What would you think for Garage, 36w? 56w might be a bit excessive for a stand alone single garage?
A single 5ft florry would be adequate, but there is no harm in doubling up and potentially having too much light.
Cheers 
£25/hr sounds reasonable to me, surely not more than 2 hours work for 2 lights?
Could probably bash it out quicker if you are happy having the cables clipped, but that's a fair estimate of the time it would take based on what you said in your original post.
It might only be a morning/afternoons work....including travel time....but unless he has another small job to goto, you might find he prices it as a days work 
A cowboy would probably chance his arm at pushing for a days work, but it's no more than a couple of hours (give or take) based on the initial description, and that's exactly what it would get charged as.
@ Mark,
If you supply the light fittings, I'll supply the cable and switch, install the lot (cable clipped to wall), do the test, and issue the certificate (small works in this case) for £130 all in.
The above price is subject to looking at the job first, but if I am interpreting your first post correctly (you want it cheap as chips, but legal and looking half tidy), then the above price stands.