Obs flights are usually completed by an OBS purser or No.1. Most are OK. Just be yourself, smile a lot and revise your SEP beforehand. All CC were new once and the OBS P/No.1 will take that into account. The mechanics of the job you will learn in time. Whether you are suited to it 'personality' wise is another matter. That's down to whether you are a people person, a smiler, punctual, smart and bother to maintain a good working knowledge of SEP.
If you can do all of the above, you're a trained professional who will love the job for a long time. Monarch will prove a happy home for you.
If you're not, you end up being the 'trolley dolley' that joe public often associates with the profession.
The choice, as they say, is yours.
Good luck, but the title 'Manky' Monarch, I would say, isn't a good choice?