Expect a court summons (rather than a fixed penalty notice).
If it was actually 90mph (rather than, say, 91mph) expect a fine of 75% of your weekly take home pay, plus costs (perhaps £80), plus a £15 'victim surcharge', together with 3 penalty points.
Just over 90mph would bring about the risk of an immediate ban but you'd probably be fined (at a level similar to, or slightly higher than above), with perhaps 4 (or up to 6) penalty points.
See here:
http://www.pepipoo.co...trates_guidelines.htm
Chris