Welcome to the club. I'd highly recommend Duncan Graham @racedynamix. He mapped my car and done a brilliant job and I hear nothing but praise for him from other members. He is mainly based at Surrey rolling road but it is well worth the travel.
I see you are in Greenwich, we have a couple of members local to you and we hold a monthly meet in greenhithe near Bluewater.
As for power, with the mods you have I'd suggest you change to a 3 port boost solenoid (if it's UK) and upgrade the fuel pump. Just for safety. What fuel do you run on? If you use high octane like momentum 99 you will have a higher chance of good figures. Lastly, with a TD04 turbo and your set up you'll make 270-280 if it has a TD05 you could see up to 320.
I'm gonna send you a pm with a few details [emoji5]