Welcome Stu :D
Might be best to start off a new thread on this, so people here can more easily spot your question. You can use the "New Topic" button to start a new thread.
An induction kit won't make much difference to bhp, if at all, the OEM induction is pretty good. I've put a K&N panel filter in my OEM induction, which is more free-flowing (as well as lasting longer), which improves mpg very slightly and slightly changes the engine note.
Induction kits make a nice noise and look good under the bonnet, IMHO that's their main benefit. The Prolex one does seem to be quite well-rated, in that it routes the induction away from the hot exhaust manifold (quite a few kits run the induction right over the manifold, which will be counterproductive since that will heat up the intake air). The Prolex one is here.
Aztecbandit1 has made some great postings about how to make your own induction kit, try using the search button and looking for "induction".
The primary recommendation for me would be to get your car's geometry set up properly, the OEM setup results in a lot of premature tyre wear and poor handling. Since you're in Ireland, a trip to Wheels in Motion to sort this out probably isn't on, but other members in Ireland might be able to help recommend a place to get this done. Also, if you join LOC as a Gold member then Tony Bones at LOC can help make sure it gets done properly to the correct settings.
An HID upgrade kit is relatively cheap these days (approx £50 off eBay) and is a great mod.
Lots of other things you can do of course, depends if you want to alter the looks, handling, performance (but that typically costs lots of £££££ !) etc.