This year I have grown tomatoes for the first time myself rather than just getting them off my Mum, they took a long timer before they started ripening and now that they are doing, im puzzled. The fruits are lovely and juicy ( some are splitting ) but they are very bitter, they taste very much like tomatoes should except for the bitterness. We have had very little sun this summer and a large amount of heavy rain. I am wondering if the lack of sun has affected the sweetness of the fruits as it is not just the one plant but both of the ones that have ripened which are different types, have i just been unlucky with the type of plant or has the lack of sun affected the developement of the sugars in the fruits?
I researched this for you, and it sounds like the abundance of rain in your area may be the problem (according to the link below.) I would make tomato sauce, and add sweetener . . .
Check your soil PH value. Add lime if it is low. Acid soil will produce bitter tomatoes. Also, what fertilier do you use? You need use fertiliers specially made for tomatoes. They have very high K, which is the essential element for tomato to produce sugar. Heavy rain may wash away K in soil. If you can get straw and wood ash, apply them to your plants. They are akline and have very high K element. Cool temperature may also contribute to unsweeten fruits (sour or even bitter).