I would suggest a grow bag but empty it into a container of some sort. I use something similar to this. I don't bother in the glasshouse but get some trays for them to stand in if you can.
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One of the most important aspects of growing tomatoes is watering. Tomatoes benefit significantly from consistent watering with a measured regular amount, they do not like flood or drought. My method is this. Get a two litre plastic drinks bottle, cut the bottom off and make three small holes in the lid. Bury a 9cm (3.5") pot in the compost to a depth which allows the bottle to sit, cap end down, in to the pot but without touching the base. Using this method you can control the amount of water the plants receive. Half filled bottle is one litre etc. I grow two plants per trough and use one bottle per trough filling it up once per day is usually sufficient. Water in the evenings when needed. In your situation this will also help minimise water draining through etc.
You may struggle to find tomatoes in supermarkets etc. at the moment. I've been keeping my open as the nursery I usually use is closed. Can I suggest you choose cherry types as these will form smaller, branched plants than the traditional large types. There is also far less cultivation involved in cherry types, no side-shooting etc. The flavour is genearlly more intense.