Just because your baby is in the nursery doesn't mean you need to stop breastfeeding! In general, nurseries and nurses agree to give babies breast milk, under certain hygienic conditions (cold chain, transport, storage, etc.) and packaging (use of sterile single-use bags, etc.) The best is to talk about it directly at the time of registration!
In the UK, you should be able to pump at your workplace if you wish. You can request that your employer provides you with a suitable private space where you can do this. The guidelines here recommend that you have access to a private, clean and comfortable room with a lockable door - not a toilet - in which to express. However, there is no legal obligation for your employer to provide this space
It's also recommended that you have use of a fridge to store your breast milk.