[danzvtil]

I've done all this before.
You can make an offer on the house subject to it being vacant possession on settlement date. It will then be up to to vendor to ask the tenant to vacate, they may offer the tenant some incentive to move before their lease on the property is up.BUT if the tenant does not agree, they cannot be forced to go before time.
I once bought a house with a tenant who had 2 months to go that I was going to move into. I agreed to let the tenant remain until end of lease, but I lowered my offer to take into consideration my messing around/possible capital gains liability on what will be a principle place of residence and to cover the risk that said tenant may turn out to be the Manson family.
Dunno what the current situation is regarding this tho.