Grow Mediums Westland gro sure all purpose

[Thedon88]

So thanks to this lockdown the only soil/compost I can find anywhere is this "Westland gro sure all purpose compost" it says it feeds plants for 4 months!! This seems like a bad thing too me as there may be too much or too little nutrients. Has anyone used and had experience using this composr or similar? I think it may be hard to add extra nutes and fix any problems but may be wrong?? I am going outdoor this year with auto mazar and auto glueberry og. Any help appreciated

 

[Thedon88]

So I've got a bag of Westland top soil(last bag in store) could I mix my compost with that say a 2part soil 1part compost??