Baby formula

Hi guys quick question, myself & my husband are planning on buying some baby formula for when our baby is born and we want to stock up abit but we are worried that baby might not like the milk, do you think its a good idea to still stock up or not? I dont think we can return it after we bought it so yeah dont want to spend alot of money just in case baby doesn't like it, has it happened to anyone else before where baby didnt agree with formula and also which formula would you buy UK? My son was on aptamil but its abit expensive so just want your opinion on other baby milk that is good for babies and healthy, i do plan on breastfeeding but with my son i was struggling very much, i couldn't get him to latch properly so just want to have some baby milk in house just as emergency