Howdy Sam, welcome.

If you've got room for a bench you can pull out, go with that, locking casters work pretty well if you have to wheel stuff about, even for a bench you are going to plane on.
If you've nowhere big enough for a bench to stay, make something that knocks down (moravian, or something simpler), I just made a sawhorse sized bench that fits in a fairly small corner, a low roman bench would do similar that could fit in a smallish bit of free space (Or double as a coffee table).

Depends on the size of the little room you have (And for hand tools only you can go pretty small).
If there was no room for a bench I'd make a narrow (12-18") bench to stay outside as a starting point and work the rest out from there - you could expand to a knockdown bench, or just keep it as is and add a sawhorse of the same height if you end up wanting to use sheet goods.

As always, a lot of what you want to build makes a big difference to what kind of workshop you want to end up with - could turn out you really like whittling and just need a rocking chair to chill in ;)