I know nothing about about road bikes, so what's good, what do you recommend, what should I look out for and what should I avoid?
thank you.

I bought a Boardman Team for £800, worth checking out

http://www.boardmanbikes.com/road/road_team.html

Pros:
Very light for the price
Very good transmission
Overall very good value

Cons:
Doesn't look as cool as some £800 bikes from bigger manufacturers
Bizarelly thin bar tape that needs to be changed straight away!
Halfords staff are variable – make sure you can either set up a bike yourself, or know someone who can, just in case you have to deal with a turkey.

Most major manufacturers will have decent bikes at £800, although spec is rarely as good as the Boardman. If you can find a decent discount somwehere it might be worth a squirt.

Failing that try secondhand. Road bikes tend to keep condition better than MTB's and you could get something very nice for £800.

EDIT: Halfords currently giving £50 accessory vouchers with the Boardman.

thank you i'll be having a look at that.

One of these second-hand from me….. how tall are you?

It's for the mrs, she's 5'5

If she doesn't mind a triple this is really very good value and in available small sizes:

http://www.wiggle.co.uk/p/cycle/7/Focus_Variado_Expert_Triple_2009/5360037596/

It's possibly better value than the Boardman, even if it is a little heavier.

Oh, and you will probably need to decide first whether you ever want to use full-length mudguards or panniers. The bikes I have been linking to cannot take panniers, and only take 'race' mudguards.

Thats no good then, its a large for 5'10" to 6'2"

should probably go for womens specific, saving you saddle changes etc

spesh