Scooby will suit all your requirements apart from their a bit juicy,not as bad as some people say but your talking mid 20's realistically day to day.long runs they can be really good but your a young loon and you WILL want to floor it now and again,more often than not!!!!

Golf gti turbo would be my choice,appalling as standard but literally a chip and remap gets your 200bhp.
Watch gearboxes though,can be a real weak point,although they can be repaired for £250/300 you'll still have to get it in and out,if you can't do it yourself it's gonna be a £5-600 job,(including the box) but you'll probably want to throw a new clutch in as well so another £150 on top,starts looking expensive then,my suggestion would be get one that's had the repair done first.
Mileages not really an issue with them,seem to get better with age.

Personally I like the astras and they do seem cheap,there's always loads for sale on migweb but they seem a bit unloved,there's boys over there been trying to shift them a long time and just end up breaking them in the end.

A good compromise could be a mk3 astra gsi with a turbo conversion,Saab or c20/z20let.

There's plenty of these around £2.5/3k and they look nice,a bit retro and are actually very reliable.again stage one on these is 260/270 bhp and that's plenty enough in a small car like that.

You could have a chat with chip on here as to that engines ability as he's built that beast of a nova in his sig using I believe a mainly standard internally c20let.

If you want to go a little less mainstream,but not as cool then anything Swedish will give you a good history of turbocharging,a nice Saab 9-3 IMO can look really good,very strong and reliable but I'm getting ever nearer 40 so my looking cool days are long gone.

Again the volvo s40 t4/v70 t5 is a ton of car for the money,but a bit old man.

I suppose the coupe could be considered "coolish" and their a very cheap car.I was in one last year,red,leather,no rust or dents,90000 miles and it went like fuck,handled nice too,all for £1000.