New car seats all round

[mezza123]

Hi all, hoping you can help :)
I have DS (aged 3.4, 15.2kg, tall for his age) and DD (aged 10 mo, 8.6kg, v tall for her age) and a small car Skoda Fabia
DS is in Maxi cosi priori fix (group 1 seat) and DD in Maxi cosi baby size one, so they are still within the weight limits for the seats but getting a bit long. I want to keep DD erf, and possibly DS too if it's possible. But what seats to get?

DH and I are complete dunces with car seats and have an inability to fit them easily, so I think Isofix would be easiest for us.
Does anyone know of a group 1 and group 2 erf car seat, with isofix but that detaches from its base (ideally), and fits in a smallish car?
We are planning to get a bigger car though, but haven't got round to it yet and have no idea what kind it might be, apart from an estate not a hatchback.
I know my request is detailed but I thought, you never know, there might be some knowledgeable erf mumsnetters out there! With DS I didn't know you could stay rear facing past the baby seat but now I do it just seems a lot safer.
Thanks :)

I'm not sure about the car seats (my 21 month old DD2 is in a Britax Multi Tech II ERF seat, but it's a belt-fitted one), but if you like your Skoda why not look at their bigger cars? I'm sure I've heard that the Superb is a really good car for ERF with lots of room in the back. Or I think the Octavia is slightly bigger again.

Thanks Alicemum re car suggestions, I'll look into it. Is it harder to find enough room for erf seats would you say? Do u like your belt fitted seat and how hard is it.to attach?
Thanks :)

I don't know anything about them but maxi cosi are bringing out erf seats in the uk

I'm not sure any of the erf seats are isofix? I have a britax two way elite for ds2 (20mo) which ds1 had until he was 4.3 (and ds2 needed it), it fits up to 25kg so you could potentially get two of those and they are quite easy to fix (with a belt & tethers) however you do need the front seats reasonably far forward (and we have an estate car) so if either you or dh are tall then that may not be a good choice.

If you went with ff for your older dc then Ds1's seat is a group 2-3 britax kidfix xp sict, difficult to get hold of (mothercare exclusive supplier and stock levels are rubbish) but the Which best buy and an easy seat to fit/use and the side impact protection seems great (and much better than the erf seat and as ds1 is at the side of car then that makes sense to me), doesn't take up that much room either.