Irrespective of any licences you may hold, sadly for you, your conviction will prevent you obtaining an airside pass at any UK and EC airport.
One of the criteria for the granting of the issue of an airside pass is a Criminal Record Check and your past crime is listed as a disqualifying event.
Read
https://www.gov.uk/government/public...tions-aviation
The disqualification is proportionate to the disposal and time in jail.
A person shall fail the criminal records check where it reveals a conviction for a disqualifying offence which has been received within:
the last 5 years where the disposal was other than a term of imprisonment.
the last 7 years where the disposal was a prison term of 6 months or less.
the last 10 years where the disposal was a prison term of between 6 months and 2 and a half years.
within any time period where the disposal was a prison term of more than 2 and a half years.
Even if you had the licences and then committed the crime, your pass would not be issued at renewal date because you have to go through the Criminal Record Check each time.
Without the airside pass no airline would employ you.
HWB
Moderator