We prefer 8+ to 7+, 7+ feels too early (especially if you're not a winter baby): we do feel 7+ is good preparation and context for 8+ if you want to try a year early even if 8+ is the target trajectory. Schools with both a 7+ and 8+ intake do have good methods to incorporate the new boys.
In GHS missing MS1 (leaving at 7+) means missing out on some of the extras that make it a good experience (graded level music, theatrical productions etc.)
Some schools like Latymer don't have an 8+ entry, you do need to be mindful of prep goals.
In WUS, incumbents do the 11+ (not the 13+ unless going for the Challenge) it's not clear how other schools deal with this (keeping up with senior school entry) but generally the 8+ is the easy part :) There is always an exam around the corner.
Tutoring is ultimately a form of outsourcing, they're pre-prep age children and everyone was a child at some point. You either do homework with family or pay someone else to do it. It's not so much tutoring or nothing (both are technically tutoring).
I feel 7+/8+ are based on curriculum marterial, the 11+ is, 13+ is, GCSEs are, A-levels are. And yet at each of these entry points families will be tutoring (usually as they started doing it from day one and you depend on it forever).
In my opinion get the home environment right, make homework part of the ritual (review and further research around the ideas). Keep on top of the material that is based around the 7+/8+ but approach it in different contexts (outside of a desk with a pencil) like play time or games that have a NVR dimension for example.
There are other ways to build up speed and endurance used in exam conditions (but developed in home life) without every month doing a mock 8+.
There is this idea of the "flipped classroom" where homework is done at school and material is reviewed at home. I feel it succeeds as the homework experience isn't enriching enough and people just try to get it out of the way.
en.wikipedia.org/wiki/Flipped_classroom
I think what I'm saying is -- track progress, don't make it boring and everything will be fine at exam time. The finding a tutor 6 months before an exam feels very lastminte dot com.