Is £270 odd a good price for a Canon EOS 550? Or, to put it another way is that a decent camera for the money. I’ll probably want to do some macro shots (clinical dental) and maybe feed a screen by the video feed. Would probably need a macro lens of some sort I guess?

Same place has a Panasonic GF1 for £224 . . . Would that work?

You will need a macro lens and some kind of macro flash – ring type ideal , and available fairly cheap now,
the old favourites were the medical nikkors with integral flash silly monrey.
The lens and flash integration will dictate the camera make .

Hmm. Canon. Macro lens from £100-400+

You don’t necessarily need a ring flash. I got by for ages without one. I assume if you are in a dentist surgery you’ve got plenty of light available.

It’s worth noting that bridge cameras are all capable of very good close-up macro work out of the box – capabilities that you would have to spend a lot of money on a second lens for a DSLR to get.

I bought a LED ring light from Amazon for £40 btw, as opposed to £200 for the Olympus ring flash unit. Works nicely and is on all the time so lets you set the shot up.