You still get paid back for road tax, TV tax, you will be exempt from land council tax, and they still have the VAT free program.
The MOT checks emissions. I'm not sure what mods you have done to your car but I know that my truck (supercharged, cammed, LT headers w/ hi-flow cats) was twice the limit for the highest emissions bracket available.
I would definately pick up whatever you want before heading over here. I have been trying to get a supercharger over here, but the kits are too heavy to ship USPS. International shipping adds a 20% import tax.
Yes I am military, I work in AGE on the Flightline.
709 RWHP, 628 RWTQ