Hi Nick
My advice would be to take them into a firearms dealer he can give advice and he can still take them into storage if you have some I.D.
The rifle is likely to obsolete caliber and potentially can be held without certificate as a display piece but you need advice on what caliber it is. The Lee Enfield if bored to .410 out can be held on a shotgun certificate. At present unless you are a certificate holder you could technically be in possession of a working firearm without a certificate....very very bad news. Most Police Licensing authorities are sensible but you are running a risk.
If you are in Newark you are near to Roy Martin Gunsmiths on the A57 Lincoln Road, I suggest giving them a call and ask their advice. They would charge you a small amount for storage until things are sorted or sold on.
There is also a small gun shop in Clayworth near Gainsborough and Kexby again near Gainsborough.
Just to add the Lee Enfield is probably the only one that would sell...always fancied one myself so let me know where you end up with it.
Cheers