Is there any point in trying to save some seed from this year's tomatos &
use them for next year' crop ?

Not if you want to grow true-to-type F1 hybrids.
If you want to grow a specific tomato(es) for taste, cropping,
disease-resistance etc then you must bite the bullet and buy some
seeds. Cross fertilised seeds are unlikely to be useful and more
than likely to be disappointing.

While this is generally true, some plants seem to breed more true to
parent than others. According to The Seed Savers Handbook (Jeremy Cherfas,
Michel & Jude Fanton, ISBN 1 899233 01 6)...

"Tomatos are self-pollinating and easy to save. ...
Tomato flowers are perfect, and the male anthers form a tube around the
female stigma. In modern varieties, the stigma does not emerge beyond the
end of the anther tube. In these varieties cross-pollination is
negligible, and breeders of modern tomatoes seperate each row by only 3
metres,..."

Seemingly some older varieties out cross more readily, and bagging of
flower trusses is recommended for those fruit providing the saved seed.

So as long as your toms are not F1s, you have a pretty good chance of the
saved seed being true to type.

My experience tends to confirm this, as I've sown saved seed tomato for
many years and they so far have come pretty true.

cheers
Jim

p.s. this book recommends leaving the fruit to ripen just beyond eating
stage, squeeze out the jelly and seed into a jar - adding a bit of water
if dry. Leave in warmth for 2-3 days for a mat to form on top of seeds,
along with fermentation acting on the sticky gel surrounding the seeds.
After 3 days remove the fungal mat, add water pour thru' a sieve. Wash and
rub seed till clean then dry on china plate or shiny paper.