^^^^ This
Rtech. I'm in Sussex and am off their next week for some TIV magic on the old girl.
As above, check/change your DV, PCV, Cam follower. They'll give your car a full health check beforehand anyway (all good tuners will do this). If you really want a more local tuner then contact the nice peeps at JKM Performance about a REVO map, they're in Potsmouth.