I like M&S light tog sleeping bags, I've got 0.5 tog and 1.5 tog
I got a really good one off Amazon https://www.amazon.co.uk/gp/aw/d/B0C27Q4KPC?psc=1&ref=ppx_pop_mob_b_asin_title £12.99
I got some good ones of shien
Snuz pod ones are pretty good
we were gifted a 1tog from next which has been great x
Asda
They have some in ASDA at the moment x
I have 1.0 tog ones from next which ive usef since he was newborn! I have a 0.5 tog one got from Sainsburys for the hot weather x
I got this 0.5tog one as our house retains heat (great in winter, AWFUL in summer) - it’s 100% cotton and so breathable ZIGJOY Baby Sleep Bag Baby... https://www.amazon.co.uk/dp/B0B3XKCP3P?ref=ppx_pop_mob_ap_share
Asda xxx
M&S or I think most supermarkets have some options