belt

hi has anybody fitted a cam belt on an astra h 1.8vvt?looking at doing mine and wanted to see if there are any dos or donts or is it a straight forward job.will use the cams locking tool but do I need a tool to lock the crankshaft on its timing mark?done a couple of chains on z22se before so...

remove air box pipe clip with screwdriver remove air box lid with the t25 screwdriver and then the air filter remover air box base by unscrewing the rear mount with the t30 then lifting the rear and sliding backwards you should now just see the tensioner under the engine mount it has a 3/8 hole...