Are you working with seedlings or are you sowing seeds directly into the planting beds?

Better to start your seeds indoors and grow them on until they are 8-12 inches high. After the tomato seedlings are acclimated to the outdoors, plant them in your newly prepared bed, in a sunny location where they'll get at least 6 hours of direct sun each day and plenty of space, don't over crowd them - 3 feet between each plant. Plant them deeply up to the top set of leaves. This will cause them to develop an extensive root system which will prevent them from drying out too quickly. The roots will grow down deep to access ground water which is much better then tap water. Work in plenty of compost, don't over fertilize. Cut off suckers growing in the crotch between mainstem & leaf branches. If you don't get bees to pollinate, give your plants the 'shaky shake' when they are in blossom.

Thank you growing from seed and only grow in a tunnel due to rabbits and deer. Doors get keft open in warmer weather as I also have mesh doors last year bought the bags as recommended and put 3 per bag and had a very poor yield, courgettes love it in there but greens bolt like gardening but because of wildlife very restricted any more suggestions for use for the tunnel? Last year bought 40 geraniums planted and the following day there were 3 all the others eaten down to the centre stalk in the ground

I use grow bag compost but put the toms into large black pots 5 litre or bigger. They then get sunk into the soil in the greenhouse. the pots I have are about 10-12 incehes in diameter. you could try growing them this way in the tunnel or stand then in the emptied grow bag and use it as a 'saucer' to hold water. I'd water well in the evening and if you can manage it in the morning too.
We also grow peppers and in cucumbers the same way.

for other crops choose ones that are resistant to bolting, where they flower and set seed too soon.
plant the less tender crops nearer the doors so they are cooler.

My only concern about planting in the green house is pollination. Bees aren't as numerous as in previous years and they'll have a hard time accessing your tomato plants. You'll have to be diligent with a paint brush or shake your plants almost daily.

You can get sprinkler systems for polytunnels which operate on a time switch.
We grow our toms in the tunnel, they are put in bottomless pots using our own compost. Peppers and Chillis the same way.

oh yes we have some of those bottomless ones too.
we never have a problem with pollination and I rarely hand pollinate. not sure what insects we have in there.

Ours is full of bees, even now. Bit of a nuisance as they are busy working the Auriculas, so the flowers are over quickly.

I usually plant sunflowers or zinnias nearby to help draw them in towards my tomatoes & peppers. It works.