Here are some situations in which having access to a storage unit before a house move could be useful.

You need to do some work on a storage area in the new house before you can put items in it

If there are storage spaces in your new home that need to undergo some work before you can put certain items in them (for example, if you need to build some shelves for an alcove in your living room before putting your books in it, or if you want to wallpaper and install a coat rack in your understairs cupboard before storing your coat collection in it), then you should consider putting the items that you plan to keep in this space into a storage unit until you've done this work.

Doing this will allow you to do this DIY work slowly and with care, rather than doing it hastily and badly because you urgently need to start using this storage area for certain items. Furthermore, if you put your items into one of your local storage company's dry, safe and clean storage units whilst you're doing this work, there will be less chance of these items getting broken in the way that they might if you temporarily stuffed them into an unsuitable storage area in your home during this period. For example, the coats that you plan to put in the unfinished cupboard would be much safer in a storage unit than they would be in an unclean, moth-filled loft, where they could end up very musty-smelling and ruined by moth holes by the time you take them out.

You've had to purchase items for your new property that have left you with less storage space

If you've purchased some new possessions for your new place, you might find that, even if the property is similar in size to your previous home, you don't have space for some of your existing belongings. For example, if your new home's garden has a huge lawn and is enclosed by hedges, and as a result of this, you've had to get a ride-on lawnmower and several hedge-trimming tools, as then you might have less free space in your new garage than you did in your old one. This might then mean that you don't have anywhere in this area to put things like sports equipment, DIY tools or magazine collections.

In this situation, it would make more sense to put these items for which you now have no space into a storage unit, instead of trying to squeeze them into random spots around your house, where they might either look out of place or take up useful storage space that you need for other things. In a storage unit, these items will be out of sight but will still be available for you to access any time you need them, and will not affect your ability to store your other possessions neatly within your home.