Al-salamu 'alaykum brother and may Allah help you to succeed insha'Allah. It is wise that you have chosen the Hanafi madhab, considering that England is predominantly Hanafi. I have noticed that many British Muslims do not know basic fiqh. So please learn some Hanafi fiqh so that you can teach and benefit others. Most questions that people have are related to their worship of fiqh so this would be a great service on your behalf. Also you should see what is most pressing in need for your community and study that. Fill in the gaps that need to be filled. You will, however, have to study for an extended time with scholars, perhaps during your summer holidays. As for seeking knowledge, generally one should take benefit from wherever it can be found. Our scholars have benefited from al-Zamakshari's tafsir even though he was Mu'tazali. Some of the most trustworthy narrators in the famous hadith collections were Shi'i or Khariji. Ijazat, although beneficial, are somewhat redundant in our age, except in Qur'an, hadith, and fiqh. These are the only subjects that connect directly to the Prophet, peace be upon him. England has quite a few people whom you can learn these from with ijazah (especially in Qur'an). Ijazat mainly serve as a blessing and it is through peer recognition, rather than certificates, that you should get by. Many scholars say that the basics are learnt with scholars, whereas most of what they have learnt is through self-study. Bitawfiq!