Which car seat - dilema

[Rosa]

Travelling to the Uk in July and using parents car - for approx 2 months. I have a ( then) 3 yr old approx 13.5kg and baby will be 7mths.
I already have britax Si in the Uk that the baby can use it is rear and forward facing.
Just don't know which seat to get for the 3 yr old. The boosters are mainly for 15kg+ .
We have the Jane Indy here but the car here has Isofix - the Uk no!
Does anybody have any suggestions - I would prefer something with extra side protection and obviously something that can be used in future years. I would like to avoid purchasing another group 1 if possible simply as I will have to get another next year !!!

Yes it's the Britax 123 just like in the link near the start of this thread, except it's black. I still have all the harness bits, I just need to reassemble them (have the instructions somewhere!). The 5 point harness is better than a standard seatbelt, even if child reaches the 15kg mark. I can have a go with the straps when kids are at school/nursery tomorrow. I was thinking around £30 + courier at cost? Let me know your thoughts!

Can do pics tomorrow too if you are interested.

Yes please to pics did you manage to fit the harness ???- As I said no rush as I dont need it until July !!! - If I don't see teh message please cat me or come and find me on Little Italy !!!

Hi Rosa, sorry didn't get a chance on Friday, will do this week, and will take some photos