Martin,
Welcome m8,
I take mine to Eden Park Motors (Upper Elmers End Rd, Opposite Eden Park Station in Beckenham 020 8658 3738) - not sure how they are on decats but were okay on my sidelight bulbs. I think these days it's hard to get round the decat thing as I believe the test is pretty much online. If you can keep your old centre section and fit it back on just for the MOT it should pass with no problems. That's what most do and what I will be doing when my decat downpipe goes on later this year.
You've got a good list of mods there mate - let us know how it goes - normally take mine to ScoobyClinic - would be interested to see how they compare.
Cheers, Matt.