Yes, EU seats can be installed with just a seatbelt or can use ISOFIX (with or without TT or footprop for anti rotation).
Depending on how long you are staying it could be cheaper to purchase seats.
www.which.co.uk is the UK equivalent of Choice and has independent safety testing results (which you have to pay to view).
In terms of capsules (up to 13kgs and approx 84cm or so)
Graco Logico S HP scores 80% (top score in this category is 82% - best buy's are over 70%)
5 stars for crash performance in frontal, side and overall. RRP is 70 pounds
The rearward-facing Group 0+ Graco Logico S HP is designed to carry children from birth up to 13kg (approximately one years-old) is secured using the adult seat belt. It can be installed on its own, or with a special base that stays, belted in the car. This makes it easier to fit and remove the seat with the baby already strapped in. To find out how well it performed in the Which? Child Car Seat tests, read the full review.
It makes the Best Buy grade in both modes, but the base costs extra.
These results are for its use without the base.
It is very easy to install in the vehicle, with clear instructions and warning labels and well-designed belt routing. Once installed, it is very stable in the car and its good padding offers excellent head support and good leg support.
Front and side crash protection is excellent, with very low loads transmitted to the child.
Funnily enough when the Graco is used with the Base it gets a score of 76% (4 frontal, 5 side, 4 overall)
In terms of seats suitable for children up to 4yrs, the seats which perform best don't have 5pt harnesses but actually a shield for the chest/tummy and use the adult seatbelt. These seats score even better then the ISOFIX 5pt harness seats. (Please don't read this that all the tummy shield seats are testing well, some test horribly - specific results to the specific seats mentioned).
Kiddy InfinityPro - 78% RRP of 120 pounds
4 stars frontal, 5 stars side and 4 stars overall
The Group 1, Kiddy Infinity Pro is forward-facing and is designed for use with children from 9kg to 18kg (approximately one to four years-old). It is secured using the adult seat belt, which feeds over and through a special 'impact shield', designed to spread the loads transmitted to the child in a crash. Read the full review and watch the video to find out how it faired in the Which? Child Car Seat tests.
This child car seat is a Best Buy. The Infinity Pro's front crash rating is good, with the child well protected from the risk of serious injury. It does even better in the side crash, where this seat scores top marks for protecting the child.
The Infinitypro is also commendably easy to fit. It's a very lightweight seat and so it's easy to handle. Feeding the seat belt over and through the seat's 'impact shield' is very straightforward, as is buckling it up with the child in position. All this is aided by very clear instructions, minimising the chances of it being fitted incorrectly. We've had reports from a few members that some children find Group 1 seats with this type of impact shield (instead of a harness), intrusive on their personal space and react negatively. In such rare cases the child might be inclined to try and push the cushion out and free themselves.
In comparison the Top 5pt harness ISOFIX seat is the Maxi Cosi Priorifix with a score of 75% (4 star frontal, 5 star side, 4 star overall) and the Britax Duo Plus (ISOFIX + Optional TT) gets a score of 70% (gets 3 star frontal, 5 star side and 4 star overall). The only other 5pt harness best buy seats are the Maxi Cosi Pebble (ISOFIX) 74%, Britax Safefix Plus (ISOFIX) 70% , Chicco Key1 ISOFIX 70%.
After that the seatbelt only 5pt harness seat which scores best is the Maxi Cosi Tobi which gets 67% ( 3 star frontal, 4 star side, 4 star overall) and the Britax King plus which gets 66% and the same star ratings.
ETA: Also just because a carseat has ISOFIX doesn't make it necessarily safer - some don't buy's are ISOFIX. Testing has shown ISOFIX superior when using the same seat shell with different connecting mechanisms. If the shell of the seat is useless it will be a useless seat no matter the connection IYKWIM?
This post has been edited by lsolaBella: 18/04/2012, 10:18 AM