Vauxhall Combo gearbox problems...

[Dab of oppo]

Hi, we have a V reg Vauxhall Combo van which is fantastic little van and does us proud on a daily basis.
Recently we have had trouble when selecting reverese i.e crunching no matter how fast, slow, hard you select gear.
The problem now seems to be with the whole gearbox as forward gears are difficult to get into - a very stiff feeling.

Could this be the clutch on its way out or the gearbox in general, there are no other signs of clutch problems i.e slipping etc.
Any help would be appreciated as our daily hack needs to be reliable!