Career change within the NHS...worried as I have to break contract

[Supermum222]

Hi,

I am hoping to change career within the NHS. Not something I had planned but due to our department closing soon (and moving to another hospital) and the demands of out of hours working at a greater distance, plus only being part time, it just is not financially worth carrying on (esp with added stress).
I am a band 6 but would like to retrain in a role that will be band 7 following training (at my previous hospital that I loved). I would also return to work full time as my children would be older then (eldest starts secondary next year). I would need to leave the NHS though and do a course paid for through the NHS bursary scheme (it is Masters level so I do qualify).
Having worked for the NHS for 17 years I am worried about what will happen if I break my NHS contract, even though I am planning on returning in a couple of years. Would I still get the same perks (ie. longer annual leave for over 10 years service, retirement lump sum) based on my current 17 years plus any future years in the other role...or, would I start back at zero for length of service? Does anyone know? I have heard you carry it over with AFC even though there is a break. I am not so worried about my pension as I would be going full time from part time so I know I could make that up.
Has anyone changed career within the NHS that could advise?

[Supermum222]

PS.
If I stayed as bank staff throughout the training would that stop the break in contract?