35°c temp in 1 year old

I'd call 111 and ask for advice. Does your little one seem fine in themselves..? What type of thermometer did you use for checking there temp.?

If that's a true reading, it's low. Seek advice from 111.

this may be a dumb questquestion but what is 111?

I know this is late but did you try taking rectal ? Sometimes under arm it doesn’t work well and also not to check it often as it read falsely but still you can always call the emergency line to be sure

111 is the NHS call service in the UK it's the steps you take before heading to urgent care or A&E.