Will I get more of a bonus because I am over 3 years?
Yes.
https://www.motaclarity.co.uk/news/how-much-is-the-motability-good-condition-bonus
Prior: SEAT Ateca Xcellence Lux 1.5 TSI DSG MY19, VW Golf GTE PHEV DSG MY23
Current: Hyundai Ioniq 6 Ultimate
Next: we'll see what's available in 2028.