Back OT.
Lets start with the basics first, rather than people calling out all sorts of shite without knowing the requirements. Sonys and Macbooks, I ask you!
I'm guessing this is primarily a business machine, mostly to run MS Office type apps, email and web. Not a consumer machine for playing games and watching films on.
Based on that, I would be looking towards an Ivy Bridge based i3 (Core i3-3xxx) or it (Core i5-3xxx). i7 overkill, and prone to reliability issues. If it brings it in budget, Sandy Bridge i3 (Core i3-2xxx) or i5 (Core i5-2xxx), the CPU itself isn't that different, but the graphics are down performancewise (compared to Ivy Bridge).
As hinted above, no discrete graphics, purely on reliability grounds. Use the Intel on CPU graphics. Battery gets a boost as a bonus.
RAM - 2-3Gb for 32bit Windows (can't use more than 3Gb anyway), 4+ for 64bit Windows. For the use I've assumed, no point going beyond 4Gb, it won't get used, and will zap the battery.
HDD - 1Tb? Have you been drinking? WTF for? If her work patterns need that amount of space (unlikely?), I'd be inclined to go with a smaller, faster drive (SSD, around 200Gb), and offline data to a cheap portable 2.5" external drive (2.5" so you don't need seperate power pack) - Windows (Business versions) can encrypt this, and the main drive, which I'm sure is a company requirement anyway?
Am I right in thinking she works from home a lot, but trundles into office fairly regularly? If so, portability is probably more important than a big, power sapping, hot screen? 'Elf and Safety will demand seperate monitors and keyboards - thats LAW! So you need a monitor port on laptop, and enough USB. Plus budget for a screen/keyboard/mouse.
On subject of budgets, Office is around £200 if you have to buy that out of the same budget.
In this case, I'd be looking at the more robust, servicable items from the likes of HP (Elitebook, Business etc, not Pavilion shite), Dell (Latitude) and Lenovo (Stinkpad) (despite my own personal objections to the Stinkpads). Not consumer oriented shite like Acer, ASUS, crApple, Tosh (as much as I love them), Sony, HP Pavilion and similar, and Dell Inspiron and similar. But you'll need to at least double your budget to just buy the base laptop, before SSDs, monitors, docks (if applicable), Office etc.
Are my assumptions correct, and am I near the mark?
Given the lack of info I've given

your pretty close. But I should have said, clearly

, that this is to replace her own personal lap top. Work have now given her a decent work only toshiba running windows 8 by the looks. This machine is strictly for work use, due to security, so she needs her own personal Dell replaced as the drive is starting to give read errors and allocating space incorrectly, I'm told.
Her own laptop will rarely leave the house. It will perform basic office tasks for tax returns and accounts, email, web, iTunes, music, photos hence storage ( ok 1 TB drive is too big, didn't appreciate draw on battery). No games. Very rarely video. She won't be happy taking it on holiday, preferring to read books or kindle anyway.
I'd say battery life is quite important, thinking about it.
If this was for work though, you'd be bang on. But by god they'd be paying for it. Not me.

So, it's purely for her own "personal work" stuff re Microsoft office, plus the normal iTunes web email storage stuff. We do have a portable 1TB drive to back up and dump stuff onto. It won't need a dock mouse or separate keyboard, (although your quite right that she should be using those on her work lappy) as she uses her own away from a desk in personal leisure time.
In all honesty she's had nothing but agro with her Dell. Battery's fail so often she's given up and just uses the power lead automatically. There's been numerous call outs from Dell tech. It crashes causing the screen to go blocky if its picked up in the wrong way. Screen res is poor IMO, it's been replaced for dead pixels two or three times, and the second something goes wrong with it I instantly get the blame.

Although it is over 10 years old by now to be fair.
Guessing a more modest machine then? Reliable, good battery life, doesn't crap itself when "picked up the wrong way" with decent response times. ...?
