Help needed - race car electrics

[Sigmamark7]

I should be racing my Clio at Castle Combe in the Saloons today, but despite the car running perfectly on Friday evening, on Saturday morning it wouldn't start. It seems to have immobilised itself, but unlike previous occasions, this time it won't even turn over on the starter. I tried all the immobiliser resets and even tried towing it, but still nothing.
Since I am £225 down in lost entry fee, it seems sensible to get some proper attention for the electrics to avoid the same thing happening again, so does anyone know somewhere in the South West where I can take it to get the Alarm and immobiliser disconnected to simplify the electrics?