If somebody has no Nationality card of UK, is he able to practice in UK court, although he has completed BPTC courses?
Practising as a barrister in England and Wales requires more than completing academic courses, as Wikipedia will tell you; passing yourself off as a barrister on the basis of a Canadian qualification and a few courses will probably land you in prison. It is not a requirement that you hold British nationality; foreign lawyers can and do represent clients - once they have qualified in England as well.
(As asked, your question could also cover Scotland and Northern Ireland, and indeed qualifying as a solicitor (in which case you probably will not practise in court). However, if you are not clear on all the differences, you will not be allowed to practise anyway.)
Firstly, you must have a practising certificate to be able to practice reserved legal services (exercising rights of audience, probate activities, conducting litigation etc).
Anyone supplying such services without a practising certificate is committing a crime under the Legal Services Act 2007.
Note that providing legal advice is not a reserved legal service.
Now to answer the main question:
There are two types of lawyers in the UK, Solicitors, and Barristers.
A foreign lawyer may qualify as one or the other, but each type of lawyer has its own foreign qualification scheme. I will only speak for barristers.
A foreign lawyer may qualify as a barrister in the UK through the Qualified Foreign Lawyers Scheme
In the relevant guidance, for a person who is not a european lawyer, the requirements are:
4.5 A Qualified Foreign Lawyer may apply to the BSB for exemption from the Academic, Vocational and/or Professional Components of training. If the Qualified Foreign Lawyer has for a period of at least three years regularly exercised rights of audience in courts which administer law substantially similar to the common law of England and Wales, the BSB will grant exemption from the Academic and Vocational Components, and, if it thinks fit, from part, or all, of the Professional Component of training. Exemptions will usually be granted conditional on passing some or all sections of the Bar Transfer Test. For the purpose of 4.5 above, courts in the following jurisdictions are deemed to administer law substantially similar to the common law of England and Wales:
Anguilla Antigua & Barbuda Australia Bahamas
Bangladesh Barbados Belize Bermuda Botswana British Virgin Islands Canada Cayman Islands Dominica Ghana Grenada Guyana Hong Kong
Isle of Man Israel Jamaica Malawi Malaysia Montserrat Namibia New Zealand Nigeria Northern Ireland Pakistan Papua New Guinea Scotland Singapore South Africa Sri Lanka St Kitts & Nevis St Lucia St Vincent & the Grenadines Sri Lanka Trinidad & Tobago Turks & Caicos
United States of America Zambia Zimbabwe
Other Qualified Foreign Lawyers may be granted exemptions from the Academic, Vocational and/or Professional Components of training. Any exemptions granted would normally be subject to passing some, or all, of the Bar Transfer Test.
So it appears that a Bangladeshi lawyer can practice in the UK if they follow the necessary application procedure and prove to the UK Bar that they are an appropriately qualified foreign lawyer.
NOTE: It doesn't matter if you've completed the BPTC. That would only make you an unregistered barrister, and part of the BPTC Ethics course is knowing that unregistered barristers are not allowed to provide reserved legal services.