Masterlock do one that I believe is the only one to be Insurance approved (ie doesn't invalidate your policy).
This one maybe:
http://www.diy.com/departments/master-lock-resettable-combination-reinforced-key-safe/265025_BQ.prd
This one maybe:
http://www.diy.com/departments/master-lock-resettable-combination-reinforced-key-safe/265025_BQ.prd