Reading your post, you have no need for basic training. You should be able to complete a medical (D4 form completed by any doctor), send it in with a D2 (licence application) and your current car licence. DVLA will then issue you with a CAT C licence. You will need driver cpc (normally completed by attending 5 x 7hr classroom courses). Apply for a digicard. Then, all things being equal, you’re ready to go.
Sounds like you have the attitude that will endear you to a decent employer. Some may look at you as being a safe bet running up to your retirement, possibly IRO 5,6,7 years. The same employer could look at a 30 year old knowing that he will be up and gone as soon as someone else offers a bit more cash. So you are in a decent position. Maturity and life experience may work in your favour.
Impossible to guess how agencies may view you. But I cant see any bias tbh.
All the best with it, Pete 