I used recorded delivery with stamps. Posted by Embassy in London 22nd December still not arrived in South Yorks 3rd Jan. The UK post is in a mess !!!!!
i used recorded delivery signed for and timed out if youve got actual stamps on you are OK. If its franked you could have problems the embassy phoned me after 10 days i sent a new envelope same day and then 10 more days to return
Some people have been within a week. Mine has taken 4 weeks. I put in a recorded return envelope which was wrongand had to send a new envelope. Bank holidays Xmas post embassy in London closed for cleaning and bank holidays. Send as soon as you can there is no definite answer. Be lucky