The pronunciation of most - but not all - BBC newsreaders and presenters is known as RP, or Received Pronunciation. RP is clear, neutral and 'educated' and is what most people outside the UK would refer to as 'the British accent'. If you click on the British English icon on an online dictionary, you will hear a voice saying the word in an RP pronunciation. It is also the pronunciation you will hear on airline announcements, English exam instructions, and all sorts of other situations where clarity is important.

If you want to acquire a British style of spoken English, you should aim to learn RP. All other accents in the UK are regional. The only reason you might learn English in, for example, a Scottish or Yorkshire accent, would be if you wanted to live in that region. Otherwise, it would be very strange for an Algerian to learn a British regional accent. Your own Arabic accent mixed with, say, Scottish vowel sounds, might confuse a listener in an international context. If you aim for RP,  you stand the best chance of having a clear, standard accent which will be universally understood.