Those who wanna work in the UK (though I suggest not to come here if you are doing good job in Bangladesh) now can take the opportunity of Working Holiday Maker scheme or HSMP visa.
To get a job here you will need to have good qualification and industry experience, multiple software and numerical modeling skills will give added advantage. And of course you need to be good in English speaking and understanding.
As far I know this country needs a huge amount of civil engineers with expertise in water and environment (Can't say anything about other fields but you can check online http://www.justengineers.net/ or other sites).
With working Holiday maker visa you can work here for one year but later the company will get the work permit for you.
Before applying the visa make sure you have good practical industry experience in your field (not academic exp.) and you have good value to the company. I know people coming here with M. Engg but ending up doing odd jobs, so please do not take unnecessary risk!!!!
Please check this sites for application details
If you are here (or know someone) with work permit and good qualification, please let me know, hopefully I can arrange an interview with my company (currently the largest in this field within the UK).