On your records: medical records only? Rehabilitation of Offenders Act kicks in after 10 years for 'minor offences' criminal convictions for most UK Disclosure purposes. Already disclosed for class 2 anyway.
When you complete the ESTA for a US visa, it asks whether you have ever taken 'illegal drugs'?
Might be a show stopper unless you have diplomatic status (A1 visa)
DO NOT incur any expenditure for professional training until the Class One is issued.