Changing the headlamp is simple, I've done mine recently and i'm rubbish at most things car related!
The bulb is one you can get from halfords, I just took my old one out, then took it to the shop to compare with the ones they had.
My advice would be to leave the headlamp pod down when replacing the bulb. When you take the fuse out the light unit won't pop up, so originally I manually wound mine up to gain access. But in the end I found you get more space (and better light) by leaving the light unit down and accessing from behind. It is a bit fiddly and space is limited, but there are some cables that connect to the back of the light unit through a rubber cap protector (that stops the water getting into the light unit).
You can see in the pic below the rubber cap and the bits the cables connect too (red arrow).
Once you pull the rubber cap and cables off, there is a metal clip holding the bulb in place. You can see in the pic below it's clipped at two places (red arrows), you need to push the clip down and to the side and then it should just lift up.
Ensure when you put the replacement bulb in, that it's sitting flat where it should. When I put mine in the other day, it wasn't in flat so when I put the headlight on the beam was pointing upwards.
As for the steering, my power steering is the stiffest power steering I've ever had on a car! Also most Elan steering makes a hissing noise too when you steer.
Can't beleive the garage wouldn't even change the bulb!