[Eightball]

Blossom end rot is caused by lack of calcium by the way. Irregular watering can lead to the plant lacking said calcium but there also might not be enough in the soil/compost in the first place. Some lime or calcified seaweed added to the water once a week will help. I make up 2 Litres of solution with a couple of table spoons of lime and put a glug (accurate measurement!) in my watering can once a week.