Choosing a new graphics card

Scan is pretty popular in UK, or so I have heard...

If your budget is as you said, then a GTX660 Ti is about the best you can do from the green goblin. If you would like the red army, try an HD7950, like this one:

http://www.scan.co.uk/products/3gb-msi-radeon-hd7950-twin-frozr-oc-be-5000mhz-gddr5-gpu-880mhz-1792-cores-dvi-hdmi-mdport-plus-free

The great thing about the 7950 is that it has a full 384 bit memory bus compared to the 192 bit on the GTX 660 series (Ti or not). This will help tremendously when you use larger monitors (higher resolutions) or turn on all the eyecandy functions.

I'm not sure why the GTX660's are priced so high on Scan/in the UK...

If I waited and collated an extra $50 or so, would I be able to get anything better?

And without trying to start a flamewar, 7950 or 660Ti for 1080p next-gen gaming?

Well, my opinion based on reviews around the web (and even Toms here) is that the GTX 660 series is just GOOD for current gen 1080p at best. When you start stressing it, the 192bit bus really hobbles it. Toms said this:

"Our last few comments concern the 660 Ti's 192-bit memory interface. Our benchmarks show that this can really put Nvidia's GeForce GTX 660 Ti at a disadvantage, even at 1920x1080 and without obscene texture detail settings. Whether or not you run into a performance problem depends mostly on the game you're playing. In general, though, the card really starts to run out of steam at anti-aliasing settings at and beyond 4x MSAA. This is too bad, since the GPU goes underutilized at that point. The problem is unique to this card. None of the other Kepler-based boards experience it. We're not saying the GeForce GTX 660 Ti is a bad card, but there are competing configurations that demonstrate better balance."

From http://www.tomshardware.com/reviews/geforce-gtx-660-ti-memory-bandwidth-anti-aliasing,3283-17.html

So I would personally pick a 7950 for that price (comparatively cheaper per performance class as well). At your budget, I wouldn't touch a GTX660, or anything less than a GTX660 Ti from the green side. But that same budget buys you a lot more from red.

And what's the support for Radeon like? I had an ancient Sapphire card in my first computer, then my 550 Ti - is it just Nvidia's marketing that put it out to be favoured amongst developers?

Also, which brand of 7950 would be a good option? There's masses of difference between the brands and the reference in terms of performance, cooling and noise apparently.

Support is good. Some recent driver reviews from HardOcp concludes that while the 7000 series had a rough launch from a software/driver point of view, now a year later, they are as good as they can be.

Long review here:

http://www.hardocp.com/article/2013/02/18/2012_amd_video_card_driver_performance_review#.USvSBOiLFe4

As for branding, MSI's frozr/hawk cooler is pretty good (on average). The Asus's custom cooler is also pretty good. I wouldn't touch Sapphire. I recently understood why so many sapphire 5000/6000 series cards have seized fans, is because they used cheaper sleeve bearing fans that are KNOWN to die quickly. So Sapphire's custom cooling solutions with 80-90mm fans, I wouldn't touch at all.

Other than that, I'd only recommend from the top tier's big three - ASUS, Gigabyte, MSI as a generic rule of thumb for now. ASUS tends to have good designs but horrible support, Gigabyte has okay designs (GPUs from Gigabyte aren't as good as their mobos, is my opinion), MSI tends to have good quality stuff for the more premium products, and average or so-so for lower performance bracket products (both GPUs and MOBOs).

Excellent, thanks so much   You've been a real help!

No problem. Cheers!