Thanks, 7755matt. I've got clip on aero bars already and I've been looking at deeper section wheels. In fact it was the cost of deeper section wheels that got me thinking I might as well fully upgrade to a new bike - they're a fortune! I haven't yet tried an aero helmet, but I'm going to borrow one from a friend in a club TT and see how it feels.
People's comments about taking the plunge and buying a TT bike only to be no better (or even worse!) off is a bit of a concern, I have to say.
Thanks for all of your replies! I've been looking at Planet X and wondering about them, as they seem to be much cheaper than what appear to be similar models by other companies. I'll give them a closer look.
Also, some other suggestions here too for me to research...
FlatFoo...ted made a point I've already considered - perhaps I'm not actually good enought to warrant buying a TT bike and it's not my bike that's holding me back! I could well just be getting fished in by all of the fast-sounding carbon jobbies that come swishing past me in races. I don't think I'll settle until it's a lesson I've learned first-hand though!
I'm currently riding a road bike with clip on tri bars (when racing - when training I'm using a single freewheel road bike). My race bike is a decent (but old) road bike with Dura ace components. I've started to have a proper crack at triathlons this season and I love them, so want to continue trying to improve. (I'm not fast by any means, but I want to improve for myself). I'm wondering if the road bike position is holding me back aerodynamically and I'm thinking of taking the plunge and buying a more specific bike for competing in triathlons.
I wouldn't want to spend any more than £2000 (£2500 at a push, but don't tell my husband!)
Any advice on the best bikes in that kind of price range would be greatly appreciated!