Hi, I work in a nursing home and have done for most of my career following a short stint on a ward (qualified a few years ago). I'm adult trained so slightly different but I can give you my perspective if it helps.
Nursing homes are a completely different ballgame to the wards, in good ways as well as bad. The good outweighs the bad for me and I prefer nursing homes in general as although still under immense pressure, I get more time to provide quality care. I really enjoy my job and the people that I look after. Older adults are incredibly resilient and generally, a pleasure to care for. It's so satisfying getting to know your residents so well that you can spot if something is wrong instantly.
You will have to quickly get used to being "in charge" and making quick decisions on your own. You don't have doctors onsite and it can be difficult to decide which course of action is best at times e.g ringing a GP/ambulance/out of hours. Trust your instincts, they will help you out so much.
Listen to your care staff if they have concerns about a resident, they are your eyes and ears and will spend much more time with residents than you do.
Also, get used to delegating, you can't do it all yourself and your paperwork needs to be done unfortunately.
Thankfully, services are expanding in community and there are lots of different initiatives now to support nursing homes. Will be different in each trust but generally these services are being rolled out everywhere.
The perception of nursing home nurses is finally starting to change and we are now(finally!) being recognised as autonomous, multi skilled practitioners. Do not listen to those who tell you that you will become de-skilled, this is nonsense and those who say it have probably never worked in a nursing home 
You will learn a variety of skills, quickly, as older resident populations will generally have multiple co-morbidities. Ask what training the home offers, it varies widely and can really make a difference. The more skilled you are, the less you have to rely on district nursing etc. There is nothing more frustrating than being the only nurse on and not being able to fix something right then and there because you aren't trained.
I would make sure that you work in a place where you are not the only nurse and don't get left alone and in charge until you feel very confident.
If they say they are willing to support you as a new nurse, ask how. How long will you shadow someone for? How long will it be till you are left as nurse in charge?
Re lifting etc: generally the nurses do medicines, OBS, wounds, palliative care etc, however in my experience, nurses can be told to cover for care staff and work the floor when short staffed. This varies from place to place but is generally standard practice. I would ask if this happens in this home and explain your concerns re your back issues.
Good luck with everything and congratulations on completing your course! 