Absolutely. Because you have to work backwards. You have th think where you want to end up, and where you need to be to get there.
In Kent,N this working backwards often goes;
OXbridge - Super selective Grammar/independent - Prep school - Private nursery feeder to Prep
So in fully selective counties such as Bucks and Kent private primaries (Preps) are often a huge thing - people what to pay for primary in order to avoid paying at secondary level and to give the best chance of getting a place. Those hyper set on Grammar don't tend to think 'I will go for my bit if social mixing to see all of society at a young age' because they fear this will wreck the chances of the coveted grammar place.
Of course, people do go to Oxbridge from good Comps, average Comps and occasionally sink Comps. Lots also go to all the other great Unis too and most of these kids have been to state primaries of varying success.
If you seriously want Grammar though, some thought is needed in terms of how you will get your kid in. Have a look at the 11+ forum website for this - there are people crazily planning literally a campaign of attack from birth, but also those thinking through a few months of familiarisation. Some kind of familiarisation at least is certainly advisable when you remember that the majority who sit the 11+ cannot pass and some people have worked for years to get a place.
I think OP would benefit from looking at the regional pages on the 11+ forum website. They will give more of a flavour of the grammars, plus the primaries.
And I must say I find this idea that the Grammar or Indie is supposed to be exciting because it is a step up from a less impressive primary experience quite odd. Children are excited by starting secondary because it's the next stage. It doesn't have to be more shiny than the last stage for this. Remember,N they have to actually get in, so the primary phase, plus any extra help needs to be good enough to get them there.