As mentioned, Ideally you'll want a decent TBE with 200 cell cat. Up to you which one you go for, look at BCS, Milltek or Blueflame. I have the BCS Sports Powervalve 200 cell TBE and its immense off and on boost (but that's just me). Cost, £1k+
Add an intake system and bobs you mother brother, your ready for Stage 2. Check out REVO, EVOMS or ITG/VWR for a decent intake, from £300-£450. An intercooler and HPFP will be a benefit at any stage of tune, even stock will benefit from both but neither are
really necessary at stage 2.
Look at checking or updating or changing (pre tune) your cam follower, Diverter Valve, PCV and Coilpacks.
Some peeps get slip on stage 1, some don't get any on stage 2+ So plan on needing it (whether you do or not is another thing). Its as much down to the way you drive as the clutch condition. Look at the linear maps on offer, less aggressive than some others. Clutches of choice are Sashs or Helix and generally if its for road use a new DMF is what your after. Budget about £1k+.
Happy modding.