There are probably others that know more about Tomatoes than I do, but I'll tell you what I know... leaf curl in a Tomato is usually a sign of some form of stress.
Lack of or too much water, cold weather, aphids (tiny green bugs on the under side of the leaf), verticillium wilt, fungus.
If the plant looks healthy, no yellow leaves, or leaf spots, you don't see any insects and it seems to be thriving, then it is probably due to the chilly, damp weather that you mentioned you were experiencing and I probably wouldn't worry too much. It should be okay once it gets warm/hot and the sun shines.
After my tomatoes get some height, I will remove the bottom leaves so that they don't touch the soil, this prevents soil fungus from splashing on the leaves when I water or it rains. Tomatoes need 1 inch of water a week. I water new plants more... until they get established Make sure the soil is soaked through. I use a liquid fertilizer for tomatoes every week and top dress with a granular fertilizer once a month ( liquid-after a rain, granular - before a rain). Try not to water/fertilize in the heat of the day. We have cutworms here, so I stick a nail in the soil next to the stem. A cutworm wraps itself around the stem at the soil line and chews the plant off at the base, the nail prevents this.
Bull's heart produces a large sweet pink flesh fruit, that can weigh up to 2 pounds. That's a big tomato.
If you still have room, I would plant some Roma's, they are great to eat and freeze well and stay firm when you use them in cooking.