Tomatoes

Would  greenhouse tomatoes do better if planted in the large compost bags instead of the small growbags,as i had a poor crop last year, they seemed to stop growing.Would the extra compost help or would it be a waste of money/space.

Some people turn gro bags on their end to get a bigger depth of compost or put pots into the hole in the gro bag to get a bigger depth.
They do need a lot of feeding though - maybe that was the problem.
I plant all mine outside because they get scorched in the greenhouse and feed them liberally with comfrey tea. I also plant them too close together, don't stake them properly and get a good crop, these last two years anyway.

For all of us, we have to try a variety of toms to see what we like. My favourite is a low acid yellow one, which others find bland. My friend prefers them more tart, another friend prefers them drier. Each to his own taste is a very  good saying when it comes to toms.
Try to not grow the same varieties you find in the grocery shops, nor the very common seeds available everywhere. Check around for some recommended unusual seeds like the old heirloom toms which are still available if you look. That's why you're growing yours - better flavour.