To apply for the Myanmar visas you can do it through post and pay extra for postage, or you can apply at the London Embassy personally. 
 You can download the visa form from  myanmarembassylondon.com/…20Visa
 
To apply for visas In Person or Representative which takes 3-5 working days
 
1) Download the Visa form, print and fill it. I wrote the name of my hotel for the reference.
2) Two recent Photos
3) £14 cash

 I went to Myanmar Embassy in London to apply for the visas in the morning of Thursday (10 am to 12 am). There is a ticket system and I waited in the waiting room. The waiting room has writing desks in case you have not downloaded or filled the form. I waited 10 minutes for my turn, I handed the clerk at the reception the downloaded application form, the passport, two pictures and £14 cash.
There were two clerks serving at the counter so it was fast; I waited further 5 minutes for him to check the form and he gave me the receipt for my passport. I was out of the Embassy in total of 15 minutes. The clerk told me to pick up the passport on Tuesday afternoon. I went after 4 days to pick up my passport with visa stamp at 3 pm in the afternoon from Myanmar London Embassy. I would have gone sooner but there were tube strikes in London on wed/ Thur. It went very smoothly and I only waited 2 minutes at the reception.

To collect stamped passport you have to visit the Embassy in the afternoon between 2 -4 pm but do ask them the correct time to pick up the passport. Check if they have entered the correct name on the visas and you are ready to visit Myanmar.
Happy Planning:)
 
The address of Myanmar Embassy in London is 
   19a Charles Street
   London W1J 5DX

To apply by post then;
 
 1) Download the Visa form, print and fill it.
2) Two recent Photos
3) £14 postal order or cash
4 ) Prepaid Special delivery SAE Envelope ( Return) 
Send it by Recorded delivery to the Embassy. You will hear from them within 10 days.
  
Please beware as Myanmar does not do visas on arrival, my daughters friend in Hong Kong was not allowed to go to Myanmar as she thought she could get visas on arrival and she lost out on all her money on the flights and hotel bookings.