Most £8k Tekna's will be on 11 bars I'd say (79 - 85% SOH) and if 12 soon to be 11! You could download Leafspy and an OBD dongle to find out the precise SOH.
Depends on your usage but if it's mainly local journeys and you have access to other cars I'd probably not be too worried if it's the 3.6kW or the 6.6kW onboard charger - the latter was circa a £1,000 option so not that common.
We've had 3 x Leaf 24's - they're very solid cars overall, would be more concerned to get one that's been looked after well and priced fairly and do the usual car checks. It should come with the 3 pin granny charger and hopefully a type2 to type1 cable.
One thing to make sure is that it's battery owned not leased - most will be but worth making sure! If you put the reg into a site such as
Total Car Check - The lowest cost car check in the UK! and it says "Flex" then be careful as it may be leased battery. (NB you don't need to do the full check there to see if it's Flex, but I would do an HPI/ equivalent somewhere before buying one)
From a quick look something like this would appear to be a pretty safe bet IMHO: (NB car is nothing to do with me!)
https://www.autotrader.co.uk/classified/advert/202011136074805
2 owners, they've had it 4 years, low mileage, looks clean and tidy inside and out, comes with the cables, charger if you want it, pretty clean MOT history etc:
Ref Andy's post above - not sure you'd get a 30 for that money (unless a high mileage Acenta) and from what I've seen they suffer from worse battery degradation (more cells packed into the same space) so don't have better batteries!
Edit: In case you're not aware I'd say for an 11 bar Leaf24 you're looking at ballpark 60 mile range this time of year and say 80 in Summer but YMMV!