Update: I got the reentry permit. As was stated by many I needed the TM8, 1 passport photo and 1000 baht. 30 minutes in total. Thanks all.
Travelling back to the UK for 3 weeks. I currently have Non-O visa and will need a re-entry permit for when I come back. Is there any particular documentation required. I already have the visa extended to 1 year and will be travelling back to Thailand before my next 90 day report is required. Any advice is appreciated.