Hi Luke.
Welcome to LOC and congratulations on your wise purchase.
I'm no expert on lowering kits, apparently the Tein kits are very good but someone else is better to advise you on this.
As for brakes, few options. A popular setup on here is the Mintex pads with standard discs or Mintex pads with Mintex discs - quite cheap on ebay - around £110 for a set of 2 discs and pads. The redstuff and greenstuff pads have got their fans but they also have a healthy amount of people who don't like them for various reasons. Black diamond stuff is very good. If it was me, I'd go with the Mintex pads and discs - there is much less brake dust and increased stopping power all at a decent price too. If you wanted just pads, the Mintex ones work very well with the OEM discs - although the consensus on here is that at around £60 for pads and £110 for discs too it makes economical sense to buy the lot. Just pop in a wee search on the forum for 'pads' or similar and you'll get a whole load of posts that should come in handy.
K&N is a good buy for induction purposes, couple it to a performance exhaust (again I'm not the one to advise on the best) and you'll get an increased bhp. Consider changing your spark plugs for some Denso IK20's they're good plugs and increase power slightly.
Websites: www.prolex-uk.com, www.wheelsinmotion.co.uk, www.lextasy.com, fleabay is good too for discs, pads, induction kits and other bits and bobs
Go to see Dr Tony Bones at wheels in motion in Hemel Hempstead to get your geometry sorted properly - a lot of us have been and the difference it makes to your car's handling and feel is huge. This should be on your top priorities list - you will not regret it. Consider new tyres, Goodyear Eagle F1's are just brilliant.
We all like photos so get some snaps of your car on asap.
Welcome to the club, keep the posts coming.
Keith