not a lawyer, but have had some dealings with employment law in the past...
the one thign I'd say to you is EVIDENCE. Get a paper trail, keep a diary, do things by email, get witnesses (e.g. a colleague to verify your understanding of an instruction before your manager throws work back in your face) etc etc etc. I've been on the other side of the fence trying to get rid of someone who was a right royal PITA to employ, did nothing etc. etc. despite this it still took an age to get rid of them lawfaully.
constructive dismissal is (AIUI) usually claimed when the employer has made it impossible for the employee to carry out their duties, and often involves a breach of contract by the employer. also it might be an idea to line up an employment lawyer to support you NOW so they can advise you on the best situation - that way you know where you stand rather than trying to build the case after you're gone.
FWIW if it's a large company they are unlikely to go to court over a CD case - the negative media reporting can cause more damage than an out of court settlement.
some info at
http://www.worksmart.org.uk/rights/v...on.php?eny=224 http://www.compactlaw.co.uk/monster/empf8.html
Naturally the best solution is to try to resolve this amicably with your boss - raise a grievance through HR and have a face to face meeting with your boss to discuss the situation, but make sure someone from HR sits in to arbitrate (that evidence thing again)