Since the law changed in the UK last year when dd was outgrowing her 6 mths to 4 years seat (at age about 3 1/2, 3 3/4) we bought a Maxi Cosi one - John Lewis says this about it:
Suitable for Group 2 and 3 (15-36kg) the Rodi XP car seat features Side Protection System for optimum safety for your child. The height and width adjustable backrest can also be adjusted to different angles to fit most cars.
With padded head support and safety hooks to ensure seat belt secures in the correct position. Also converts to a booster seat.
All our car seats and infant carriers comply with current European regulations ECE R44-03.
Age from About 4 - 12 years
Group 2 and 3
Weight 15 to 36kg (33lb - 79lb)which will take her till she is about 8. It has side impact protection, head restraint, arm rests.
It cost about GBP 95 - you can get eg a Graco one for about half that but the quality lookhd as though it would not last so we felt a false economy - this one is lovely and solid. It sits on a small base thing but is not attached to the car as firmly as a baby seat would be. DD is strapped in using the adult rear seat belt which is guided though special slots for her comfort and safety. We have been very pleased with it. Your one looks v solid - but will an 8 year old really be happy to use 5 point harness? Just a thought...
Hope this helps
I am 46, married to DH (same age) for 19+ years, with DD aged 8 and DS aged 3. M/cs Sep 04, Oct 05, Dec 05.