Milton Cold water tablets or own brand from Tesco. I bought this tub for £3.50 and use the Milton tablets. Takes 15 mins and the water lasts 24 hrs. https://www.wilko.com/en-uk/q-box-storage-box-with-handle---clear/p/8366978?gclsrc=aw.ds&gad_source=1&gbraid=0AAAAADr56JcuSdvFyCf8OVuWIZwdETpAR&gclid=CjwKCAjwwqfABhBcEiwAZJjC3nnYC77tp6BR05FDjK3w0huDXQVI5eizOuwqFIg1j5zF6Ngr3tbtfRoCYmwQAvD_BwE
I brought a collapsible bucket with lid from amazon to use with cold water and Milton tablets so just what we do at home quick and easy x
I got the nuna travel uv steriliser and also the tommy tippee set which works with pouches -so less to sterilise https://amzn.eu/d/5fMbrIq
If no microwave id buy a Milton cold water sterilising unit