Enough? When to stop tomato trusses?

I'm new to gardening, so sorry if this is the 43rd time this question has been asked this year:

I have a Gardener's Delight and a Supersweet that have reached the greenhouse roof and I have pinched out the top growth. My question is: should I also take off the higher (less-developed) flowers and will this enable the lower trusses to ripen faster, or does it not make a difference?

I am worried that I am asking too much of my plants, and that they might not ripen at all due to overwork! The Supersweet in particular must have around 12 sets of flowers already, GD has around 9, I think. I feed every second watering with Tomorite and have taken off all armpits and quite a few leaves (but reading Bigmallys 'Brutal' post I may have defoliated a bit too much).

After nearly two months of green tomatoes doing nothing, the lowest fruits on each plant have only just started blushing at last, (hooray!!) I'm in Edinburgh so do I have enough growing season left to ripen all these trusses or should I take lots of them off so my plants don't drop dead from exahustion?!

Thanks for any replies.

Pinns.