Mate, it's worth what it would cost to replace. Don't fall into that trap.

My tip: Get rid of bulky furniture or LOAN it out to friends or relations....probably halve your storage space needs. Don't rent a locker/unit bigger than you need. It's amazing how much you can cram in. Practice in your smallest bedroom, to give you an idea. Most standard units are around 8 feet high, so stuff can be stacked up.

Make sure there is 24 hr access, so when you've just got off that plane, jetlagged, and you want your transistor radio and those comfortable shoes, you can just go in and get them.

Here's a bit of useful info':

http://www.homesandproperty.co.uk/property-news/news/self-storage-units-real-cost-owning-too-much-stuff