I've had two previous ITB builds. They were great (but, sadly, very short-lived). I'm now going boosted and wish I had done from the start. I'm an NA lover but wish I'd stuck to NA mod's for the Type-R and simply gone boosted on the Clio from day one. On personal experience I do think the F4R is better suited to boost (although there is always a risk when considering and implementing modifications).
If you want the noise and drama (and nicely responsive feel) then ITB's and cams are a great option. But - I always say this - you need to be realistic and temper your expectations as to the potential gains. They aren't massive but they are noticeable. And the sound and aesthetics of an ITB build are always good on the eye and ear. If you go with a relatively mild ITB setup (ITB's, cams) then depending on how healthy your engine is then a genuine 200bhp+ is achievable. Possibly more with a good engine, map and mild mods elsewhere. If you're looking for high power NA then the cost increases significantly as you'll need to look at lairy cams, forged components, high compression, block / head work, maybe solid lifters. You are suddenly looking at thousands of pounds more and the result will still only get you to around where a low boost Clio would be at (and with less torque). Such a high-powered NA wouldn't be good for a daily driver either and would really be better suited to weekend fun and track days.
As you are looking at a drive-in, drive-out service I would guess you don't have the time or expertise to do the work yourself so would probably be looking at a few thousand pounds for a nicely sorted ITB build (nothing too mad). Personally I would put those few thousand towards a low boost setup and enjoy that.