Voluntarily reducing hours - can I retain long service benefits?

[Catkinsthecatinthehat]

I'm starting a degree as a mature student in a month's time. My employer is keen to keep me on part time and my preference is to reduce my commitment from a full 5 day week to 2.5 days (20 hours) which they are happy with.

What's the best way to go about this? I've got a child so could technically make a request for flexible working even though that's not the real reason I plan to reduce hours. Will I need to sign a new contract? My main issue is I've built up a longer leave entitlement a result of long service with this employer - would a new contract retain this (27 days - obviously pro rata when I go p/t) or take me back to a 'new starters' position (23 days)?

Thanks for any help.

[InternationalPower]

Yes, you will have a new contact, just the same as if you changed role/were promoted on a f-t basis, but you'll still have continuous service so nothing should change in terms of your holiday entitlement (apart from it being pro-rata). At least mine didn't

[Catkinsthecatinthehat]

Thanks InternationalPower

[Metalgoddess]

I've reduced my hours and holiday entitlement has remained the same other than being pro rata. The length of service is exactly the same.