I have one of these. https://www.amazon.co.uk/gp/offer-listing/B002T99CRW/ it does the job well and feels as though it might last forever.
Have had mine for 10+ years, it's been been used on a daily basis for at least 5 of those years and mine still looks almost new. Very impressed with the build quality of these. Heat my food up in the microwave before leaving for work at around 6:30am. At 12pm it's still hot and sometimes I've not eaten until 3pm when it's still "warm to hot" - still perfectly fine for eating. Wouldn't be without one now. The only niggle I have is that after washing it up water can get between the plastic and metal part of the lid, but this is easily drained out and not a big issue.
Have some of these (but slightly older top incarnation but same base). Even pre-heated the hot /cold statements for these were BS, they just about survive with noodles for 4-5 hours being "warm" When pre-chilled in a freezer overnight the chill aspect was crud. However your kid wont complain of getting their lip burnt, & with spoon & milk will be ok fo a muesli & milk breakfast. Vastly overpriced.
There's one in Argos for £11.99 for 500ml if anyone is shopping from there otherwise not a bad deal 🔥🔥 https://www.argos.co.uk/product/8688620?cmpid=GS001&_$ja=tsid:59156|acid:444-797-0832|cid:756382225|agid:71026955237|tid:pla-293946777986|crid:352905771050|nw:g|rnd:17812433172812994625|dvc:m|adp:1o3|mt:|loc:9046184&gclid=Cj0KCQjwi43oBRDBARIsAExSRQGPws81Mvtw95GJrKYbgctl8P16z97ehhUKxkQ2xiILBgzoAASpj8QaAoSyEALw_wcB
Matching Tesco. They have these on offer for £13.50 if anybody has a Tesco nearby and doesn't have prime.