I've recently built a pair of speakers using Jordan JX92s'. I'm
considering boosting the low end using a resistor/inductor network.
Before doing this I'd like to measure the frequency response of the
speakers in their cabinets.

I was considering generating white noise on my pc and recording it to
CD. Then play this through the speakers and record back onto my PC to
analyse the frequency response.
Is this a good way to analyse speakers?

I need to get a mic for the job, either with a flat response or with a
known response so I can adjust my frequency response readings
accordingly.
What type of mic do I need, where could I get one in the UK (online
sources)?

Thanks in advance
Ivan