The peak season for English schools in Malta is July, especially the 2nd and 3rd week of the month.
During this time of the year schools can be overcrowded, usually classes are full with the maximum number of students and it will be a bit difficult for schools’ staff to be flexible and attend to your specific requests once you are on site.
But I understand summer is the best time to travel abroad, so I strongly recommend that if you would like to learn English in Malta in July and August, you plan at least 3 months in advance. It is also vital that you choose the right course not to be disappointed after.

Budget wise, English schools apply a high season supplement. It means that during summer (June-September) English courses are more expensive than during the rest of the year. The high season supplement can be €40-€60 per week. If you decide to book accommodation with the school, you will also have to pay the high season supplement on the accommodation.
On the contrary, winter is the best time of the year to grab special offers to learn English in Malta .