Where do I start?

2 weeks ago I bought an L reg 306 for £525 and that weekend I got
stuck in traffic and had a problem with the wiring for the fan. In
short, the fuse for the fan kept on blowing every time the fan kicked
in at about 90 degrees.

This problem got fixed but led to another problem - my radio had been
disabled and I had to enter a radio code to activate it again. I've
had the code, but I couldn't fathom how to enter the code on to the
machine (I know now - you have to press '1' six times, '2' 5
times etc). As I tried to work out what was going on I hit upon the
idea of taking the battery out to reset the radio - not only did this
not reset the radio, but now every time you try and turn on the engine
you here a beeping noise and the alarm light starts flashing. Worse
than this you can't start the engine. Thus I assume the car has been
immobilised - I know I' very stupid, but does anyone have a
solution for me?
Guess what, I had exactly the same problem.
Normally the immobiliser is switched off by the remote central locking plip,
so after replacing the battery, lock and unlock the car with the plip.
If this is not working (as in my case) you need to put the key in the
ignition, then hold down the alarm button on the RH of the steering column,
then turn the ignition on to the normal run position. the immobiliser will
be switched off.